•

MML Blend Fund

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Initial Class

Service Class

•

MML Equity Fund

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Initial Class

Service Class

•

MML Inflation-Protected and Income Fund

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Initial Class

Service Class

•

MML Invesco Discovery Large Cap Fund

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Class II

Service Class I

•

MML Invesco Discovery Mid Cap Fund

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Class II

Service Class I

•

MML iShares® 60/40 Allocation Fund

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Class II

Service Class I

•

MML iShares® 80/20 Allocation Fund

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Class II

Service Class I

•

MML Managed Bond Fund

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Initial Class

Service Class

•

MML Short-Duration Bond Fund

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Class II

Service Class I

•

MML Small Cap Equity Fund

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Initial Class

Service Class

•

MML U.S. Government Money Market Fund

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Initial Class

INVESTMENT OBJECTIVE

This Fund seeks a high total return.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. The expenses in the table do not reflect deductions at the separate account level or contract level for any charges that may be incurred under a variable life insurance or variable annuity contract. If these charges were reflected, the fees and expenses in the table would be higher.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

​

(1)

Because Total Annual Fund Operating Expenses include Acquired Fund Fees and Expenses, they may not correspond to the ratios of expenses to average daily net assets shown in the “Financial Highlights” tables in the Prospectus, which reflect the operating expenses of the Fund and do not include Acquired Fund Fees and Expenses.

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Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in each share class of the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment earns a 5% return each year and that the Fund’s operating expenses are exactly as described in the preceding table. If separate account or variable life insurance or variable annuity contract expenses were included, overall expenses would be higher. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio

turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 7% of the average value of its portfolio.

INVESTMENTS, RISKS, AND PERFORMANCE​

Principal Investment Strategies

The Fund is a “fund of funds” that seeks to achieve its investment objective by allocating substantially all of its assets among exchange-traded funds (“ETFs”) providing exposures to various asset classes. The Fund’s subadviser, BlackRock Investment Management, LLC (“BlackRock”), determines the Fund’s asset allocation strategy and implements this strategy by selecting ETFs for investment and determining the amounts of the Fund’s assets to be invested in each. The ETFs BlackRock will consider for investment by the Fund will provide exposures to U.S. equity securities or to fixed-income securities. The ETFs are advised by an affiliate of BlackRock.

The Fund typically invests approximately 60% of its net assets in U.S. equity ETFs and approximately 40% of its net assets in fixed income ETFs. Equity ETFs may include funds that provide exposures to, among other things, domestic equity securities, including common stocks, preferred stocks, securities convertible into common or preferred stock, rights, and warrants, of issuers of any size, as well as real estate investment trusts (“REITs”). Fixed income ETFs may include funds that provide exposures to, among other things, domestic and non-U.S. bonds, U.S. Government securities, non-U.S. sovereign obligations, mortgage-backed securities, securities below investment grade (“junk” or “high yield” bonds, including securities in default), bank loans, and cash or money market instruments.

The Fund’s equity allocation may include equity exposures chosen by reference to, for example, style (including both value and growth funds), market capitalization (including both large-cap and small-cap funds), or other factors. The Fund’s fixed-income allocation may include exposures chosen by reference to, for example, sector (including government, corporate, agency, mortgage-backed securities, and other sectors), duration (a calculation of the average life of a bond

which measures its price risk), credit quality (including securities below investment grade (“junk” or “high yield” bonds, including securities in default)), geographic location, or other factors. The percentage allocation to the various types of equity and fixed-income securities are determined at the discretion of BlackRock.

BlackRock will typically rebalance to these strategic targets on a quarterly basis. BlackRock may at any time reassess and make revisions in the Fund’s asset allocation strategy consistent with the Fund’s investment objective and strategy, including revising the weightings among the investments described above and adding or removing ETFs from the asset allocation strategy. Actual allocations between equity and fixed income investments will typically not vary from the Fund’s target asset allocations by more than 10%, although BlackRock may determine in light of market conditions or other factors that a greater variation is warranted to protect the Fund or achieve its investment goal.

ETFs in which the Fund invests may use derivatives contracts to achieve their investment objectives. Use of derivatives by an ETF may create investment leverage.

An ETF may enter into dollar roll or reverse repurchase agreement transactions. Some investments by an ETF may be restricted as to resale or otherwise considered to be illiquid. The Fund or an ETF may enter into repurchase agreement transactions. The Fund will bear a pro rata share of the ETFs’ expenses. The Fund also bears all of the risks associated with the investment strategies used by the ETFs.

Through its investments in ETFs, the Fund may at times have significant exposure to one or more industries or sectors. The Fund may hold a portion of its assets in cash or cash equivalents. A description of the ETFs in which the Fund expects to invest is included in Appendix D of the Statement of Additional Information (“SAI”).

Because the Fund will invest substantially all of its assets in ETFs advised by an affiliate of BlackRock, the Fund will not invest in ETFs advised or sponsored by others, even if they are less expensive or have better historical performance records. BlackRock does not receive a subadvisory fee for its services; it does, however, receive fees from the ETFs in which the Fund invests. BlackRock will be subject to a conflict of interest in selecting ETFs, because its selection of ETFs might appear to be influenced by the expected

effect of the selection on its revenues or other benefits of the selection to it. BlackRock has advised the Fund that, as a fiduciary to the Fund, BlackRock has a duty to put the best interests of the Fund ahead of its own interest and that, consequently, it will make investment decisions for the Fund in the best interest of the Fund to achieve the Fund’s investment objectives and not for the benefit of BlackRock.

Principal Risks

The following are the Principal Risks of the Fund. The value of your investment in the Fund could go down as well as up. You can lose money by investing in the Fund. Although the descriptions below refer to the risks relating to investment activities of the Fund, many of the risks arise due to the investment activities of the ETFs in which it invests. Certain risks relating to instruments and strategies used in the management of the Fund are placed first. The significance of any specific risk to an investment in the Fund will vary over time, depending on the composition of the Fund’s portfolio, market conditions, and other factors. You should read all of the risk information presented below carefully, because any one or more of these risks may result in losses to the Fund.

Allocation Risk There is no assurance that allocation decisions will result in the desired performance effects. There is a risk that BlackRock’s evaluations and assumptions regarding asset classes or ETFs may be incorrect in view of actual market conditions. The requirement that substantially all of the Fund’s assets be invested in ETFs advised by an affiliate of BlackRock as noted in “Principal Investment Strategies” may adversely affect Fund performance.

Risk of Investment in Other Funds or Pools The Fund is indirectly exposed to all of the risks of the underlying funds, including ETFs, in which it invests, including the risk that the underlying funds will not perform as expected. ETFs are subject to additional risks, including secondary market trading risks and the risk that an ETF’s shares may trade above or below net asset value. The Fund indirectly pays a portion of the expenses incurred by the underlying funds, which may, in the case of an ETF, include a portion of the expenses incurred below their net asset value.

Bank Loans Risk Many of the risks associated with bank loans are similar to the risks of investing in below investment grade debt securities. Changes in the financial condition of the borrower or

economic conditions or other circumstances may reduce the capacity of the borrower to make principal and interest payments on such instruments and may lead to defaults. Senior secured bank loans are typically supported by collateral; however the value of the collateral may be insufficient to cover the amount owed to the Fund, or the Fund may be prevented or delayed from realizing on the collateral. Some loans may be unsecured; unsecured loans generally present a greater risk of loss to the Fund if the issuer defaults. If the Fund relies on a third party to administer a loan, the Fund is subject to the risk that the third party will fail to perform its obligations. In addition, if the Fund holds only a participation interest in a loan made by a third party, the Fund’s receipt of payments on the loan will depend on the third party’s willingness and ability to make those payments to the Fund. The settlement time for certain loans is longer than the settlement time for many other types of investments, and the Fund may not receive the payment for a loan sold by it until well after the sale; that cash would be unavailable for payment of redemption proceeds or for reinvestment. Interests in some bank loans may not be readily marketable and may be subject to restrictions on resale. In some cases, negotiations involved in disposing of indebtedness may require weeks to complete. Consequently, some indebtedness may be difficult or impossible to dispose of readily at what the Fund believes to be a fair price. Some loans may not be considered “securities” for certain purposes under the federal securities laws, and purchasers, such as the Fund, therefore may not be entitled to rely on the anti-fraud protections of the federal securities laws.

Below Investment Grade Debt Securities Risk Below investment grade debt securities, commonly known as “junk” or “high yield” bonds, have speculative characteristics and involve greater volatility of price and yield, greater risk of loss of principal and interest, and generally reflect a greater possibility of an adverse change in financial condition that could affect an issuer’s ability to honor its obligations.

Cash Position Risk If the Fund holds a significant portion of its assets in cash or cash equivalents, its investment returns may be adversely affected and the Fund may not achieve its investment objective.

Convertible Securities Risk Convertible securities are subject to the risks of both debt instruments

and equity securities. The price of a convertible security may change in response to changes in price of the underlying equity security, the credit quality of the issuer, and interest rates. In general, the values of convertible securities tend to decline as interest rates rise and to rise when interest rates fall. A convertible security generally has less potential for gain or loss than the underlying equity security.

Credit Risk Credit risk is the risk that an issuer, guarantor, or liquidity provider of a fixed income security held by the Fund may be unable or unwilling, or may be perceived (whether by market participants, ratings agencies, pricing services or otherwise) as unable or unwilling, to make timely principal and/or interest payments, or to otherwise honor its obligations. The Fund may also be exposed to the credit risk of its counterparty to repurchase agreements, reverse repurchase agreements, swap transactions, and other derivatives transactions, and to the counterparty’s ability or willingness to perform in accordance with the terms of the transaction. The value of such transactions to the Fund will depend on the willingness and ability of the counterparty to perform its obligations, including among other things the obligation to return collateral or margin to the Fund. If a counterparty becomes bankrupt or otherwise fails to perform its obligations under a derivative contract due to financial difficulties, the Fund may experience significant delays in obtaining any recovery under the derivative contract in a bankruptcy or other reorganization proceeding. The Fund may obtain only a limited recovery or may obtain no recovery in such circumstances.

Defaulted and Distressed Securities Risk Because the issuer of such securities is in default and is likely to be in distressed financial condition, repayment of defaulted securities and obligations of distressed issuers (including insolvent issuers or issuers in payment or covenant default, in workout or restructuring, or in bankruptcy or insolvency proceedings) is uncertain. To the extent the Fund is invested in distressed securities, its ability to achieve current income for its shareholders may be diminished.

Derivatives Risk Derivatives can be highly volatile and involve risks different from, and potentially greater than, direct investments, including risks of imperfect correlation between the value of derivatives and underlying assets, counterparty default, potential losses that partially or completely offset gains, and illiquidity. Derivatives can create

investment leverage. Losses from derivatives can be substantially greater than the derivatives’ original cost and can sometimes be unlimited. If the value of a derivative does not correlate well with the particular market or asset class the derivative is designed to provide exposure to, the derivative may not have the effect or benefit anticipated. Derivatives can also reduce the opportunity for gains or result in losses by offsetting positive returns in other investments. Many derivatives are traded in the over-the-counter market and not on exchanges.

Dollar Roll and Reverse Repurchase Agreement Transaction Risk These transactions generally create leverage and subject the Fund to the credit risk of the counterparty.

Equity Securities Risk Although stocks may have the potential to outperform other asset classes over the long term, their prices tend to fluctuate more dramatically over the shorter term. These movements may result from factors affecting individual companies, or from broader influences like changes in interest rates, market conditions, or investor confidence, or announcements of economic, political, or financial information.

Fixed Income Securities Risk The values of fixed income securities typically will decline during periods of rising interest rates, and can also decline in response to changes in the financial condition of the issuer, borrower, counterparty, or underlying collateral assets, or changes in market, economic, industry, political, regulatory, public health, and other conditions affecting a particular type of security or issuer or fixed income securities generally. Certain events, such as market or economic developments, regulatory or government actions, natural disasters, pandemics, terrorist attacks, war, and other geopolitical events can have a dramatic adverse effect on the debt market and the overall liquidity of the market for fixed income securities. During those periods, the Fund may experience high levels of shareholder redemptions, and may have to sell securities at times when the Fund would otherwise not do so, and potentially at unfavorable prices. Certain securities may be difficult to value during such periods. Fixed income securities are subject to interest rate risk (the risk that the value of a fixed income security will fall when interest rates rise), extension risk (the risk that the average life of a security will be extended through a slowing of principal payments), prepayment risk (the risk that a security will be prepaid and the Fund will be required to reinvest at

a less favorable rate), duration risk (the risk that longer-term securities may be more sensitive to interest rate changes), inflation risk (the risk that as inflation increases, the present value of the Fund’s fixed income investment typically will decline), and credit risk.

Foreign Investment Risk; Emerging Markets Risk; Currency Risk Investments in securities of foreign issuers, securities of companies with significant foreign exposure, and foreign currencies can involve additional risks relating to market, industry, political, regulatory, public health, and other conditions. Political, social, diplomatic, and economic developments, U.S. and foreign government action, or threat thereof, such as the imposition of currency or capital blockages, controls, or tariffs, economic and trade sanctions or embargoes, security trading suspensions, entering or exiting trade or other intergovernmental agreements, or the expropriation or nationalization of assets in a particular country, can cause dramatic declines in certain or all securities with exposure to that country and other countries. Sanctions, or the threat of sanctions, may cause volatility in regional and global markets and may negatively impact the performance of various sectors and industries, as well as companies in other countries, which could have a negative effect on the performance of the Fund. In the event of nationalization, expropriation, confiscation, or other government action, intervention, or restriction, the Fund could lose its entire investment in a particular foreign issuer or country. There may be quotas or other limits on the ability of the Fund (or clients of the Fund’s investment adviser or subadviser) to invest or maintain investments in securities of issuers in certain countries. Enforcing legal rights can be more difficult, costly, and limited in certain foreign countries and with respect to certain types of investments, and can be particularly difficult against foreign governments. Because non-U.S. securities are normally denominated and traded in currencies other than the U.S. dollar, the value of the Fund’s assets may be affected favorably or unfavorably by changes in currency exchange rates, exchange control regulations, and restrictions or prohibitions on the repatriation of non-U.S. currencies. Income and gains with respect to investments in certain countries may be subject to withholding and other taxes. There may be less information publicly available about a non-U.S. company than about a U.S. company, and many non-U.S. companies are not subject to accounting, auditing, and financial reporting standards,

regulatory framework and practices comparable to those in the U.S. The securities of some non-U.S. companies, especially those in emerging markets, are less liquid and at times more volatile than securities of comparable U.S. companies. Emerging markets securities are subject to greater risks than securities issued in developed foreign markets, including less liquidity, less stringent investor protection and disclosure standards, less reliable settlement practices, greater price volatility, higher relative rates of inflation, greater political, economic, and social instability, greater custody and operational risks, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater volatility in currency exchange rates, and are more susceptible to environmental problems. Many emerging market countries are highly reliant on international trade and exports, including the export of commodities. Their economies may be significantly impacted by fluctuations in commodity prices and the global demand for certain commodities. In addition, pandemics and outbreaks of contagious diseases may exacerbate pre-existing problems in emerging market countries with less established health care systems. Frontier markets, a subset of emerging markets, generally have smaller economies and less mature capital markets than emerging markets. As a result, the risks of investing in emerging market countries are magnified in frontier market countries. Frontier markets are more susceptible to having abrupt changes in currency values, less mature markets and settlement practices, and lower trading volumes that could lead to greater price volatility and illiquidity. Non-U.S. transaction costs, such as brokerage commissions and custody costs, may be higher than in the United States. In addition, foreign markets can react differently to market, economic, industry, political, regulatory, geopolitical, public health, and other conditions than the U.S. market. The Fund may invest in foreign securities known as depositary receipts. Investments in depositary receipts are subject to the same risks as direct investment in foreign securities, which include market, political, currency, and regulatory risks.

Growth Company Risk The prices of growth securities are often highly sensitive to market fluctuations because of their heavy dependence on future earnings or cash flow expectations, and can be more volatile than the market in general.

Index Funds Risk Certain ETFs may attempt to track the performance of a specified index.

Therefore, securities may be purchased, retained, and sold by the ETF at times when an actively managed fund would not do so. The structure and composition of the index will affect the performance, volatility, and risk of the index and, consequently, the performance, volatility, and risk of the ETF. While the investment adviser or subadviser seeks to track the performance of the index (i.e., achieve a high degree of correlation with the index), the ETF’s return may not match the return of the index. The ETF incurs a number of operating expenses not applicable to the index, and may incur costs in buying and selling securities. In addition, the ETF may not be fully invested at times, generally as a result of cash flows into or out of the ETF.

Large Company Risk Large-capitalization stocks as a group could fall out of favor with the market, causing the Fund’s investments in large-capitalization stocks to underperform investments that focus on small- or medium-capitalization stocks. Larger, more established companies may be slow to respond to challenges and may grow more slowly than smaller companies.

Leveraging Risk Instruments and transactions, including derivatives, dollar roll, and reverse repurchase agreement transactions, that create leverage may cause the value of an investment in the Fund to be more volatile, could result in larger losses than if they were not used, and tend to compound the effects of other risks.

Liquidity Risk Certain securities may be difficult (or impossible) to sell or certain positions may be difficult to close out at a desirable time and price, and the Fund may be required to hold an illiquid investment that is declining in value, or it may be required to sell certain illiquid investments at a price or time that is not advantageous in order to meet redemptions or other cash needs. Some securities may be subject to restrictions on resale. There can be no assurance that there will be a liquid market for instruments held by the Fund at any time. The Fund may not receive the proceeds from the sale of certain investments for an extended period.

Management and Operational Risk The Fund relies on the manager’s investment analysis and its selection of investments to achieve its investment objective, and the Fund is subject to the risk that the manager’s assessment of an investment is wrong. There can be no assurance that the Fund will achieve the intended results and the Fund may incur significant losses. The Fund also runs the

risk that deficiencies in the investment adviser’s, subadviser’s, or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

Market Risk The value of the Fund’s portfolio securities may decline, at times sharply and unpredictably, as a result of unfavorable market-induced changes affecting particular industries, sectors, or issuers. Stock and bond markets can decline significantly in response to issuer, market, economic, industry, political, regulatory, geopolitical, public health, and other conditions, as well as investor perceptions of these conditions. The Fund is subject to risks affecting issuers, such as management performance, financial leverage, industry problems, and reduced demand for goods or services.

Mortgage- and Asset-Backed Securities Risk Investments in mortgage- and asset-backed securities subject the Fund to credit risk, interest rate risk, extension risk, and prepayment risk, among other risks. Mortgage-backed and asset-backed securities not issued by a government agency generally involve greater credit risk than securities issued by government agencies. Payment of principal and interest generally depends on the cash flows generated by the underlying assets and the terms of the security. The types of mortgages (for example, residential or commercial mortgages) underlying securities held by the Fund may differ and be affected differently by market factors. The Fund’s investments in mortgage-backed securities may make the Fund’s net asset value more susceptible to economic, market, political, and other developments affecting the residential and commercial real estate markets and the servicing of mortgage loans secured by real estate properties. During periods of difficult economic conditions, delinquencies and losses on commercial mortgage-backed investments in particular generally increase, including as a result of the effects of those conditions on commercial real estate markets, the ability of commercial tenants to make loan payments, and the ability of a property to attract and retain commercial tenants. Investments that receive only the interest portion or the principal portion of payments on the underlying assets may be highly volatile. Litigation with respect to the representations and warranties given in connection with the issuance of mortgage-backed securities can be an important consideration in investing in such securities, and the outcome of any such litigation could significantly impact the value of the Fund’s mortgage-backed investments.

Preferred Stock Risk Like other equity securities, preferred stock is subject to the risk that its value may decrease based on actual or perceived changes in the business or financial condition of the issuer. In addition, changes in interest rates may adversely affect the value of a preferred stock that pays a fixed dividend. Preferred stocks are also subject to additional risks, such as potentially greater volatility and risks related to deferral, non-cumulative dividends, subordination, liquidity, limited voting rights, and special redemption rights.

Real Estate Risk; REIT Risk Real estate-related investments may decline in value as a result of factors affecting the real estate industry, such as the supply of real property in certain markets, changes in zoning laws, environmental regulations and other governmental action, delays in completion of construction, changes in real estate values, changes in property taxes, levels of occupancy, losses due to natural disasters, and local and regional market conditions. Investments in REITs may be subject to risks similar to those associated with direct investment in real estate, as well as additional risks associated with equity investments. As a shareholder in a REIT, the Fund, and indirectly the Fund’s shareholders, would bear its ratable share of the REIT’s expenses and would at the same time continue to pay its own fees and expenses.

Repurchase Agreement Risk  These transactions must be fully collateralized, but involve credit risk to a Fund if the other party should default on its obligation and the Fund is delayed or prevented from recovering the collateral.

Restricted Securities Risk The Fund may hold securities that are restricted as to resale under the U.S. federal securities laws, such as securities in certain privately held companies. Such securities may be highly illiquid and their values may experience significant volatility. Restricted securities may be difficult to value.

Sector Risk The Fund may allocate more of its assets to particular industries or to particular economic, market, or industry sectors than to others. This could increase the volatility of the Fund’s portfolio, and the Fund’s performance may be more susceptible to developments affecting issuers in those industries or sectors than if the Fund invested more broadly.

Small and Mid-Cap Company Risk Market risk and liquidity risk are particularly pronounced for

securities of small and medium-sized companies, which may trade less frequently and in smaller volumes than more widely-held securities, and may fluctuate in price more than other securities. Their shares can be less liquid than those of larger companies, especially during market declines. Small and medium-sized companies may have limited product lines, markets, or financial resources and may be dependent on a limited management group; they may have been recently organized and have little or no track record of success.

Sovereign Debt Obligations Risk Investments in debt securities issued by governments or by government agencies and instrumentalities involve the risk that the governmental entities responsible for repayment may be unable or unwilling to pay interest and repay principal when due. Many sovereign debt obligations may be rated below investment grade (“junk” or “high yield” bonds). Any restructuring of a sovereign debt obligation held by the Fund will likely have a significant adverse effect on the value of the obligation. In the event of default of sovereign debt, the Fund may be unable to pursue legal action against the sovereign issuer or to realize on collateral securing the debt.

U.S. Government Securities Risk Obligations of certain U.S. Government agencies and instrumentalities are not backed by the full faith and credit of the U.S. Government, and there can be no assurance that the U.S. Government would provide financial support to such agencies and instrumentalities.

Valuation Risk The Fund is subject to the risk of mispricing or improper valuation of its investments, in particular to the extent that its securities are fair valued.

Value Company Risk The value investment approach entails the risk that the market will not recognize a security’s intrinsic value for a long time, or that a stock the investment adviser or subadviser judges to be undervalued may actually be appropriately priced.

When-Issued, Delayed Delivery, TBA, and Forward Commitment Transaction Risk These transactions may create leverage and involve a risk of loss if the value of the securities declines prior to settlement.

Performance Information

The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows changes in the Fund’s performance from year to year for Initial Class shares. The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare with those of a broad measure of market performance and two additional indexes, each of which MML Advisers believes is a better comparison for the Fund’s investment strategy (Lipper Balanced Fund Index and Custom Balanced Index). The Fund’s investment objective and investment strategy changed on November 18, 2020. The performance results shown below would not necessarily have been achieved had the Fund’s current investment strategy been in effect for the entire period for which performance results are presented. Performance shown does not reflect the fees and expenses deducted under the variable life insurance or variable annuity contract through which you invest in the Fund. If these amounts were reflected, returns would be less than those shown. Past performance is not necessarily an indication of how the Fund will perform in the future.

Annual Performance

Initial Class Shares

Average Annual Total Returns

(for the periods ended December 31, 2024)

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(1)

Effective July 24, 2024, the Russell 3000 Index replaced the S&P 500 Index as a broad measure of market performance in accordance with new regulatory disclosure requirements.

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(2)

The Custom Balanced Index is a hypothetical custom index which comprises the S&P 500 Index (60%) and Bloomberg U.S. Aggregate Bond Index (40%).

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MANAGEMENT

Investment Adviser: MML Investment Advisers, LLC (“MML Advisers”)

Subadviser(s):  BlackRock Investment Management, LLC (“BlackRock”)

Portfolio Manager(s):

Suzanne Ly, CFA is a Managing Director at BlackRock. She has managed the Fund since January 2025.

Peter Tsang is a Director at BlackRock. He has managed the Fund since January 2025.

PURCHASE AND SALE OF FUND SHARES

Shares of the Fund are generally available to separate investment accounts of variable life insurance and variable annuity contracts offered by companies such as MassMutual. An investor should consult the company issuing the investor’s

variable life insurance or variable annuity contract to determine how to make redemptions.

TAX INFORMATION

Dividends and capital gain distributions are paid to the insurance company separate accounts. Variable life insurance and variable annuity contract owners should refer to the variable life insurance or variable annuity product prospectus or consult with their own tax adviser for information regarding the tax consequences of their investment.

PAYMENTS TO INSURANCE COMPANIES AND THEIR AFFILIATES

The Fund is not sold directly to the general public but instead is offered as an underlying investment option for variable insurance contracts. The Fund and its related companies may make payments to the sponsoring insurance company (or its affiliates) or other intermediary for distribution and/or other services. These payments may be a factor that the insurance company considers in including the Fund as an underlying investment option in the variable insurance contract or may create a conflict of interest by influencing the insurance company or other intermediary to recommend the variable insurance contract over another investment. The prospectus (or other offering document) for your variable insurance contract may contain additional information about these payments.

INVESTMENT OBJECTIVES

This Fund’s primary objective is to achieve a superior total rate of return over an extended period of time from both capital appreciation and current income. Its secondary objective is the preservation of capital when business and economic conditions indicate that investing for defensive purposes is appropriate.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. The expenses in the table do not reflect deductions at the separate account level or contract level for any charges that may be incurred under a variable life insurance or variable annuity contract. If these charges were reflected, the fees and expenses in the table would be higher.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in each share class of the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment earns a 5% return each year and that the Fund’s operating expenses are exactly as described in the preceding table. If separate account or variable life insurance or variable annuity contract expenses were included, overall expenses would be higher. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs.

These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 77% of the average value of its portfolio.

INVESTMENTS, RISKS, AND PERFORMANCE​

Principal Investment Strategies

The Fund invests primarily in common stocks of companies that the Fund’s subadviser, Brandywine Global Investment Management, LLC (“Brandywine Global”), believes are undervalued in the marketplace. While the Fund does not limit its investments to issuers in a particular capitalization range, Brandywine Global currently focuses on securities of larger size companies. Under normal circumstances, the Fund invests at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in common stocks, preferred stocks, securities convertible into common or preferred stocks, and other securities, such as warrants and stock rights, whose value is based on stock prices. The Fund typically invests most of its assets in securities of U.S. companies, but may invest up to 25% of its total assets in foreign securities and American Depositary Receipts (“ADRs”), including emerging market securities. The Fund may use futures contracts for hedging or investment purposes as a substitute for investing directly in securities. Use of derivatives by the Fund may create investment leverage. The Fund may at times have significant exposure to one or more industries or sectors. The Fund may hold a portion of its assets in cash or cash equivalents.

Brandywine Global employs a bottom-up, value-based investment approach in selecting securities for the Fund. Brandywine Global invests in securities that meet its value criteria, primarily, price-to-earnings, price-to-book, price momentum, and share change and quality, based on both quantitative and fundamental analysis. Brandywine Global expects to hold approximately 175 – 250 stocks under normal market conditions.

Brandywine Global invests in securities of companies that meet its value criteria based on both quantitative and fundamental analysis. Brandywine Global’s investment process begins with a valuation screen that identifies large-capitalization stocks with favorable financial ratios.

A quantitative deselection process is then applied to eliminate equities that have poor price momentum or high share issuance. Finally Brandywine Global performs a thorough fundamental analysis which seeks to identify and eliminate (de-select) companies with deteriorating fundamentals, anticipated earnings declines, or material write-offs. Brandywine Global may also consider additional factors in its selection process.

Brandywine Global typically sells a security of a company when Brandywine Global believes it is no longer a large-capitalization value company, if the company’s fundamentals deteriorate, when an investment opportunity arises that Brandywine Global believes is more compelling, or in order to realize gains or limit potential losses. However, Brandywine Global may retain securities of companies that no longer meet its initial purchase criteria.

Principal Risks

The following are the Principal Risks of the Fund. The value of your investment in the Fund could go down as well as up. You can lose money by investing in the Fund. Certain risks relating to instruments and strategies used in the management of the Fund are placed first. The significance of any specific risk to an investment in the Fund will vary over time, depending on the composition of the Fund’s portfolio, market conditions, and other factors. You should read all of the risk information presented below carefully, because any one or more of these risks may result in losses to the Fund.

Equity Securities Risk Although stocks may have the potential to outperform other asset classes over the long term, their prices tend to fluctuate more dramatically over the shorter term. These movements may result from factors affecting individual companies, or from broader influences like changes in interest rates, market conditions, or investor confidence, or announcements of economic, political, or financial information.

Derivatives Risk Derivatives can be highly volatile and involve risks different from, and potentially greater than, direct investments, including risks of imperfect correlation between the value of derivatives and underlying assets, counterparty default, potential losses that partially or completely offset gains, and illiquidity. Derivatives can create investment leverage. Losses from derivatives can be substantially greater than the derivatives’ original cost and can sometimes be unlimited. If

the value of a derivative does not correlate well with the particular market or asset class the derivative is designed to provide exposure to, the derivative may not have the effect or benefit anticipated. Derivatives can also reduce the opportunity for gains or result in losses by offsetting positive returns in other investments. Many derivatives are traded in the over-the-counter market and not on exchanges.

Foreign Investment Risk; Emerging Markets Risk; Currency Risk Investments in securities of foreign issuers, securities of companies with significant foreign exposure, and foreign currencies can involve additional risks relating to market, industry, political, regulatory, public health, and other conditions. Political, social, diplomatic, and economic developments, U.S. and foreign government action, or threat thereof, such as the imposition of currency or capital blockages, controls, or tariffs, economic and trade sanctions or embargoes, security trading suspensions, entering or exiting trade or other intergovernmental agreements, or the expropriation or nationalization of assets in a particular country, can cause dramatic declines in certain or all securities with exposure to that country and other countries. Sanctions, or the threat of sanctions, may cause volatility in regional and global markets and may negatively impact the performance of various sectors and industries, as well as companies in other countries, which could have a negative effect on the performance of the Fund. In the event of nationalization, expropriation, confiscation, or other government action, intervention, or restriction, the Fund could lose its entire investment in a particular foreign issuer or country. There may be quotas or other limits on the ability of the Fund (or clients of the Fund’s investment adviser or subadviser) to invest or maintain investments in securities of issuers in certain countries. Enforcing legal rights can be more difficult, costly, and limited in certain foreign countries and with respect to certain types of investments, and can be particularly difficult against foreign governments. Because non-U.S. securities are normally denominated and traded in currencies other than the U.S. dollar, the value of the Fund’s assets may be affected favorably or unfavorably by changes in currency exchange rates, exchange control regulations, and restrictions or prohibitions on the repatriation of non-U.S. currencies. Income and gains with respect to investments in certain countries may be subject to withholding and other taxes. There may be less information publicly available about a non-U.S.

company than about a U.S. company, and many non-U.S. companies are not subject to accounting, auditing, and financial reporting standards, regulatory framework and practices comparable to those in the U.S. The securities of some non-U.S. companies, especially those in emerging markets, are less liquid and at times more volatile than securities of comparable U.S. companies. Emerging markets securities are subject to greater risks than securities issued in developed foreign markets, including less liquidity, less stringent investor protection and disclosure standards, less reliable settlement practices, greater price volatility, higher relative rates of inflation, greater political, economic, and social instability, greater custody and operational risks, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater volatility in currency exchange rates, and are more susceptible to environmental problems. Many emerging market countries are highly reliant on international trade and exports, including the export of commodities. Their economies may be significantly impacted by fluctuations in commodity prices and the global demand for certain commodities. In addition, pandemics and outbreaks of contagious diseases may exacerbate pre-existing problems in emerging market countries with less established health care systems. Frontier markets, a subset of emerging markets, generally have smaller economies and less mature capital markets than emerging markets. As a result, the risks of investing in emerging market countries are magnified in frontier market countries. Frontier markets are more susceptible to having abrupt changes in currency values, less mature markets and settlement practices, and lower trading volumes that could lead to greater price volatility and illiquidity. Non-U.S. transaction costs, such as brokerage commissions and custody costs, may be higher than in the United States. In addition, foreign markets can react differently to market, economic, industry, political, regulatory, geopolitical, public health, and other conditions than the U.S. market. The Fund may invest in foreign securities known as depositary receipts. Investments in depositary receipts are subject to the same risks as direct investment in foreign securities, which include market, political, currency, and regulatory risks.

Large Company Risk Large-capitalization stocks as a group could fall out of favor with the market, causing the Fund’s investments in large-capitalization stocks to underperform investments that focus on small- or medium-capitalization

stocks. Larger, more established companies may be slow to respond to challenges and may grow more slowly than smaller companies.

Value Company Risk The value investment approach entails the risk that the market will not recognize a security’s intrinsic value for a long time, or that a stock the investment adviser or subadviser judges to be undervalued may actually be appropriately priced.

Cash Position Risk If the Fund holds a significant portion of its assets in cash or cash equivalents, its investment returns may be adversely affected and the Fund may not achieve its investment objective.

Convertible Securities Risk Convertible securities are subject to the risks of both debt instruments and equity securities. The price of a convertible security may change in response to changes in price of the underlying equity security, the credit quality of the issuer, and interest rates. In general, the values of convertible securities tend to decline as interest rates rise and to rise when interest rates fall. A convertible security generally has less potential for gain or loss than the underlying equity security.

Hedging Risk The Fund’s attempts at hedging and taking long and short positions in currencies may not be successful and could cause the Fund to lose money or fail to get the benefit of a gain on a hedged position. If expected changes to securities prices, interest rates, currency values, and exchange rates, or the creditworthiness of an issuer are not accurately predicted, the Fund could be in a worse position than if it had not entered into such transactions.

Liquidity Risk Certain securities may be difficult (or impossible) to sell or certain positions may be difficult to close out at a desirable time and price, and the Fund may be required to hold an illiquid investment that is declining in value, or it may be required to sell certain illiquid investments at a price or time that is not advantageous in order to meet redemptions or other cash needs. Some securities may be subject to restrictions on resale. There can be no assurance that there will be a liquid market for instruments held by the Fund at any time. The Fund may not receive the proceeds from the sale of certain investments for an extended period.

Management and Operational Risk The Fund relies on the manager’s investment analysis and its selection of investments to achieve its investment

objective, and the Fund is subject to the risk that the manager’s assessment of an investment is wrong. There can be no assurance that the Fund will achieve the intended results and the Fund may incur significant losses. The Fund also runs the risk that deficiencies in the investment adviser’s, subadviser’s, or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

Market Risk The value of the Fund’s portfolio securities may decline, at times sharply and unpredictably, as a result of unfavorable market-induced changes affecting particular industries, sectors, or issuers. Stock and bond markets can decline significantly in response to issuer, market, economic, industry, political, regulatory, geopolitical, public health, and other conditions, as well as investor perceptions of these conditions. The Fund is subject to risks affecting issuers, such as management performance, financial leverage, industry problems, and reduced demand for goods or services.

Preferred Stock Risk Like other equity securities, preferred stock is subject to the risk that its value may decrease based on actual or perceived changes in the business or financial condition of the issuer. In addition, changes in interest rates may adversely affect the value of a preferred stock that pays a fixed dividend. Preferred stocks are also subject to additional risks, such as potentially greater volatility and risks related to deferral, non-cumulative dividends, subordination, liquidity, limited voting rights, and special redemption rights.

Quantitative Models Risk The portfolio managers use quantitative models as part of the idea generation process. Quantitative models are based upon many factors that measure individual securities relative to each other. Such models may not produce the intended results and can be adversely affected by errors or imperfections in the factors or the data on which measurements are based, changing sources of market return or market risk, human error, or any technical issues with the design, construction, implementation, or maintenance of the models.

Sector Risk The Fund may allocate more of its assets to particular industries or to particular economic, market, or industry sectors than to others. This could increase the volatility of the Fund’s portfolio, and the Fund’s performance may be more susceptible to developments affecting issuers in those industries or sectors than if the Fund invested more broadly.

Small and Mid-Cap Company Risk Market risk and liquidity risk are particularly pronounced for securities of small and medium-sized companies, which may trade less frequently and in smaller volumes than more widely-held securities, and may fluctuate in price more than other securities. Their shares can be less liquid than those of larger companies, especially during market declines. Small and medium-sized companies may have limited product lines, markets, or financial resources and may be dependent on a limited management group; they may have been recently organized and have little or no track record of success.

Valuation Risk The Fund is subject to the risk of mispricing or improper valuation of its investments, in particular to the extent that its securities are fair valued.

Performance Information

The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows changes in the Fund’s performance from year to year for Initial Class shares. The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare with those of a broad measure of market performance and an additional index that MML Advisers believes more closely reflects the market segments in which the Fund invests (Russell 1000® Value Index). Performance shown does not reflect the fees and expenses deducted under the variable life insurance or variable annuity contract through which you invest in the Fund. If these amounts were reflected, returns would be less than those shown. Past performance is not necessarily an indication of how the Fund will perform in the future.

Annual Performance

Initial Class Shares

Average Annual Total Returns

(for the periods ended December 31, 2024)

​

(1)

Effective July 24, 2024, the Russell 3000 Index replaced the Russell 1000 Value Index as a broad measure of market performance in accordance with new regulatory disclosure requirements. The Fund continues to use the Russell 1000 Value Index as a supplemental benchmark that MML Advisers believes more closely reflects the market segments in which the Fund invests.

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MANAGEMENT

Investment Adviser: MML Investment Advisers, LLC (“MML Advisers”)

Subadviser(s): Brandywine Global Investment Management, LLC (“Brandywine Global”)

Portfolio Manager(s):

Joseph J. Kirby is a Portfolio Manager at Brandywine Global. He has managed the Fund since December 2017.

Henry F. Otto is a Managing Director and Portfolio Manager at Brandywine Global. He has managed the Fund since December 2017.

Steven M. Tonkovich is a Managing Director and Portfolio Manager at Brandywine Global. He has managed the Fund since December 2017.

PURCHASE AND SALE OF FUND SHARES

Shares of the Fund are generally available to separate investment accounts of variable life insurance and variable annuity contracts offered by companies such as MassMutual. An investor should consult the company issuing the investor’s variable life insurance or variable annuity contract to determine how to make redemptions.

TAX INFORMATION

Dividends and capital gain distributions are paid to the insurance company separate accounts. Variable life insurance and variable annuity contract owners should refer to the variable life insurance or variable annuity product prospectus or consult with their own tax adviser for information regarding the tax consequences of their investment.

PAYMENTS TO INSURANCE COMPANIES AND THEIR AFFILIATES

The Fund is not sold directly to the general public but instead is offered as an underlying investment option for variable insurance contracts. The Fund and its related companies may make payments to the sponsoring insurance company (or its affiliates) or other intermediary for distribution and/or other services. These payments may be a factor that the insurance company considers in including the Fund as an underlying investment option in the variable insurance contract or may create a conflict of interest by influencing the insurance company or other intermediary to recommend the variable insurance contract over another investment. The prospectus (or other offering document) for your variable insurance contract may contain additional information about these payments.

INVESTMENT OBJECTIVE

This Fund seeks to achieve as high a total rate of real return on an annual basis as is considered consistent with prudent investment risk and the preservation of capital.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. The expenses in the table do not reflect deductions at the separate account level or contract level for any charges that may be incurred under a variable life insurance or variable annuity contract. If these charges were reflected, the fees and expenses in the table would be higher.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

​

(1)

The expenses in the above table reflect a written agreement by MML Advisers to cap the fees and expenses of the Fund (other than extraordinary legal and other expenses, Acquired Fund Fees and Expenses, interest expense, expenses related to borrowings, securities lending, leverage, taxes, and brokerage, short sale dividend and loan expense, or other non-recurring or unusual expenses such as organizational expenses and shareholder meeting expenses, as applicable) through April 30, 2026, to the extent that Total Annual Fund Operating Expenses after Expense Reimbursement would otherwise exceed 0.64% and 0.89% for Initial Class and Service Class shares, respectively. The Total Annual Fund Operating Expenses after Expense Reimbursement shown in the above table may exceed these amounts, because, as noted in the previous sentence, certain fees and expenses are excluded from the cap. The agreement can only be terminated by mutual consent of the Board of Trustees on behalf of the Fund and MML Advisers.

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Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in each share class of the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment earns a 5% return each year and that the Fund’s operating expenses are exactly as described in the

preceding table. If separate account or variable life insurance or variable annuity contract expenses were included, overall expenses would be higher. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 70% of the average value of its portfolio.

INVESTMENTS, RISKS, AND PERFORMANCE​

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in inflation-indexed bonds and other income-producing securities. Inflation-indexed bonds are instruments indexed or otherwise linked to general measures of inflation because their principal is typically adjusted to reflect general movements of inflation in the country of issue. The Fund may invest in securities of any maturity. The Fund may invest in inflation-indexed bonds issued by the U.S. and non-U.S. governments or their agencies or instrumentalities, by government-sponsored enterprises, or by corporations. The Fund expects to enter into total return swaps based on one or more inflation indexes or on inflation-indexed bonds or other inflation derivatives, as a substitute for purchasing certain inflation-indexed bonds or otherwise to adjust the inflation-sensitivity of the portfolio. Use of total return swaps will create leverage in the Fund.

The Fund may also invest in other income-producing securities of any kind (including, but not limited to, corporate bonds and notes, Rule 144A securities, U.S. and non-U.S. government and agency or instrumentality bonds, money market instruments, and mortgage-related and asset-backed securities, including collateralized bond and loan obligations). The

Fund may enter into repurchase agreement transactions. The Fund may at times have significant exposure to one or more industries or sectors. The Fund may hold a portion of its assets in cash or cash equivalents. The Fund may invest up to 15% of its total assets in securities that are not denominated in U.S. dollars. The Fund may purchase and sell securities on a when-issued, delayed delivery, to-be-announced, or forward commitment basis.

The Fund may invest in (i) securities denominated in currencies of emerging market countries, (ii) fixed income securities or debt instruments issued by emerging market entities or sovereign nations and/or (iii) debt instruments denominated in or based on the currencies, interest rates, or issues of emerging market countries. Emerging market countries are defined to include any country that did not become a member of the Organization for Economic Cooperation and Development (O.E.C.D.) prior to 1975 and Turkey.

The Fund may invest in other investment companies, including investment companies that are advised by the Fund’s investment adviser, subadviser, sub-subadviser, or its affiliates, or by unaffiliated parties.

The Fund generally intends to maintain a dollar-weighted average credit quality of A or better (determined on the basis of the highest credit rating of the Fund’s investments at the time of their purchase or, if unrated, determined to be of comparable quality by the Fund’s subadviser, Barings LLC (“Barings”), or sub-subadviser, Baring International Investment Limited (“BIIL”)). The Fund will invest primarily in assets rated investment grade at the time of purchase (rated Baa3 or higher by Moody’s, BBB- or higher by Standard & Poor’s or the equivalent by any other nationally recognized statistical rating organization (“NRSRO”), or, if unrated, determined to be of comparable quality by Barings or BIIL) but not in assets rated below Ba3 by Moody’s, below BB- by Standard & Poor’s and the equivalent by any NRSRO. In the event that a security is downgraded after its purchase by the Fund, the Fund may continue to hold the security if Barings or BIIL considers that doing so would be consistent with the Fund’s investment objective. The Fund invests in a portfolio of securities that Barings or BIIL expects to provide an attractive rate of real return. Barings or BIIL defines “real return” as the portfolio’s total return (before expenses) less the estimated rate of inflation, measured using the Consumer Price Index for All Urban Consumers (the “CPI-U”).

In addition to the total return swaps and other derivatives referred to above, the Fund may (but is not obligated to) use a wide variety of exchange-traded and over-the-counter derivative transactions, including, but not limited to, total return swaps (for hedging purposes or to adjust various portfolio characteristics, including the duration (interest rate volatility) of the Fund’s portfolio, or as a substitute for direct investments), interest rate swaps (for hedging purposes, to adjust various portfolio characteristics, including the duration (interest rate volatility) of the Fund’s portfolio, or as a substitute for direct investments), credit default swaps (for hedging purposes or as a substitute for direct investments), and futures contracts, foreign currency futures and forward contracts, including derivatives thereof (for hedging purposes, to adjust various portfolio characteristics, including the duration (interest rate volatility) of the Fund’s portfolio, or as a substitute for direct investments or to gain market exposure). The Fund may also enter into forward commitment transactions. The Fund may invest in common stocks, exchange-traded funds (“ETFs”), or other equity securities and derivatives thereof for hedging purposes or to enhance total return. The use of such techniques may have the effect of creating investment leverage in the Fund.

In selecting investments for the Fund, Barings or BIIL seeks to construct a portfolio of inflation-indexed and other income-producing securities and other financial instruments, including derivatives, designed to meet the real return objective of the Fund. Barings or BIIL may choose to sell securities with deteriorating credit or limited upside potential compared to other securities.

Principal Risks

The following are the Principal Risks of the Fund. The value of your investment in the Fund could go down as well as up. You can lose money by investing in the Fund. References in this section to the Fund’s subadviser may include any sub-subadvisers as applicable. Certain risks relating to instruments and strategies used in the management of the Fund are placed first. The significance of any specific risk to an investment in the Fund will vary over time, depending on the composition of the Fund’s portfolio, market conditions, and other factors. You should read all of the risk information presented below carefully, because any one or more of these risks may result in losses to the Fund.

Fixed Income Securities Risk The values of fixed income securities typically will decline during

periods of rising interest rates, and can also decline in response to changes in the financial condition of the issuer, borrower, counterparty, or underlying collateral assets, or changes in market, economic, industry, political, regulatory, public health, and other conditions affecting a particular type of security or issuer or fixed income securities generally. Certain events, such as market or economic developments, regulatory or government actions, natural disasters, pandemics, terrorist attacks, war, and other geopolitical events can have a dramatic adverse effect on the debt market and the overall liquidity of the market for fixed income securities. During those periods, the Fund may experience high levels of shareholder redemptions, and may have to sell securities at times when the Fund would otherwise not do so, and potentially at unfavorable prices. Certain securities may be difficult to value during such periods. Fixed income securities are subject to interest rate risk (the risk that the value of a fixed income security will fall when interest rates rise), extension risk (the risk that the average life of a security will be extended through a slowing of principal payments), prepayment risk (the risk that a security will be prepaid and the Fund will be required to reinvest at a less favorable rate), duration risk (the risk that longer-term securities may be more sensitive to interest rate changes), inflation risk (the risk that as inflation increases, the present value of the Fund’s fixed income investment typically will decline), and credit risk.

Inflation-Linked Securities Risk Such securities may change in value in response to actual or anticipated changes in inflation rates in a manner unanticipated by the Fund’s portfolio manager or investors generally. Inflation-linked securities are subject to fixed income securities risks. When inflation is low, declining, or negative, the Fund’s performance could lag the performance of more conventional bond funds. Inflation rates may change frequently and drastically as a result of various factors, including unexpected shifts in the domestic or global economy (or expectations that such policies will change), and the Fund’s investments may not keep pace with inflation, which may result in losses to the Fund’s investors.

Credit Risk Credit risk is the risk that an issuer, guarantor, or liquidity provider of a fixed income security held by the Fund may be unable or unwilling, or may be perceived (whether by market participants, ratings agencies, pricing services or otherwise) as unable or unwilling, to make timely principal and/or interest payments, or to otherwise

honor its obligations. The Fund may also be exposed to the credit risk of its counterparty to repurchase agreements, reverse repurchase agreements, swap transactions, and other derivatives transactions, and to the counterparty’s ability or willingness to perform in accordance with the terms of the transaction. The value of such transactions to the Fund will depend on the willingness and ability of the counterparty to perform its obligations, including among other things the obligation to return collateral or margin to the Fund. If a counterparty becomes bankrupt or otherwise fails to perform its obligations under a derivative contract due to financial difficulties, the Fund may experience significant delays in obtaining any recovery under the derivative contract in a bankruptcy or other reorganization proceeding. The Fund may obtain only a limited recovery or may obtain no recovery in such circumstances.

Derivatives Risk Derivatives can be highly volatile and involve risks different from, and potentially greater than, direct investments, including risks of imperfect correlation between the value of derivatives and underlying assets, counterparty default, potential losses that partially or completely offset gains, and illiquidity. Derivatives can create investment leverage. Losses from derivatives can be substantially greater than the derivatives’ original cost and can sometimes be unlimited. If the value of a derivative does not correlate well with the particular market or asset class the derivative is designed to provide exposure to, the derivative may not have the effect or benefit anticipated. Derivatives can also reduce the opportunity for gains or result in losses by offsetting positive returns in other investments. Many derivatives are traded in the over-the-counter market and not on exchanges.

Foreign Investment Risk; Emerging Markets Risk; Currency Risk Investments in securities of foreign issuers, securities of companies with significant foreign exposure, and foreign currencies can involve additional risks relating to market, industry, political, regulatory, public health, and other conditions. Political, social, diplomatic, and economic developments, U.S. and foreign government action, or threat thereof, such as the imposition of currency or capital blockages, controls, or tariffs, economic and trade sanctions or embargoes, security trading suspensions, entering or exiting trade or other intergovernmental agreements, or the expropriation or nationalization of assets in a particular country, can cause

dramatic declines in certain or all securities with exposure to that country and other countries. Sanctions, or the threat of sanctions, may cause volatility in regional and global markets and may negatively impact the performance of various sectors and industries, as well as companies in other countries, which could have a negative effect on the performance of the Fund. In the event of nationalization, expropriation, confiscation, or other government action, intervention, or restriction, the Fund could lose its entire investment in a particular foreign issuer or country. There may be quotas or other limits on the ability of the Fund (or clients of the Fund’s investment adviser or subadviser) to invest or maintain investments in securities of issuers in certain countries. Enforcing legal rights can be more difficult, costly, and limited in certain foreign countries and with respect to certain types of investments, and can be particularly difficult against foreign governments. Because non-U.S. securities are normally denominated and traded in currencies other than the U.S. dollar, the value of the Fund’s assets may be affected favorably or unfavorably by changes in currency exchange rates, exchange control regulations, and restrictions or prohibitions on the repatriation of non-U.S. currencies. Income and gains with respect to investments in certain countries may be subject to withholding and other taxes. There may be less information publicly available about a non-U.S. company than about a U.S. company, and many non-U.S. companies are not subject to accounting, auditing, and financial reporting standards, regulatory framework and practices comparable to those in the U.S. The securities of some non-U.S. companies, especially those in emerging markets, are less liquid and at times more volatile than securities of comparable U.S. companies. Emerging markets securities are subject to greater risks than securities issued in developed foreign markets, including less liquidity, less stringent investor protection and disclosure standards, less reliable settlement practices, greater price volatility, higher relative rates of inflation, greater political, economic, and social instability, greater custody and operational risks, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater volatility in currency exchange rates, and are more susceptible to environmental problems. Many emerging market countries are highly reliant on international trade and exports, including the export of commodities. Their economies may be significantly impacted by fluctuations in

commodity prices and the global demand for certain commodities. In addition, pandemics and outbreaks of contagious diseases may exacerbate pre-existing problems in emerging market countries with less established health care systems. Frontier markets, a subset of emerging markets, generally have smaller economies and less mature capital markets than emerging markets. As a result, the risks of investing in emerging market countries are magnified in frontier market countries. Frontier markets are more susceptible to having abrupt changes in currency values, less mature markets and settlement practices, and lower trading volumes that could lead to greater price volatility and illiquidity. Non-U.S. transaction costs, such as brokerage commissions and custody costs, may be higher than in the United States. In addition, foreign markets can react differently to market, economic, industry, political, regulatory, geopolitical, public health, and other conditions than the U.S. market. The Fund may invest in foreign securities known as depositary receipts. Investments in depositary receipts are subject to the same risks as direct investment in foreign securities, which include market, political, currency, and regulatory risks.

Mortgage- and Asset-Backed Securities Risk Investments in mortgage- and asset-backed securities subject the Fund to credit risk, interest rate risk, extension risk, and prepayment risk, among other risks. Mortgage-backed and asset-backed securities not issued by a government agency generally involve greater credit risk than securities issued by government agencies. Payment of principal and interest generally depends on the cash flows generated by the underlying assets and the terms of the security. The types of mortgages (for example, residential or commercial mortgages) underlying securities held by the Fund may differ and be affected differently by market factors. The Fund’s investments in mortgage-backed securities may make the Fund’s net asset value more susceptible to economic, market, political, and other developments affecting the residential and commercial real estate markets and the servicing of mortgage loans secured by real estate properties. During periods of difficult economic conditions, delinquencies and losses on commercial mortgage-backed investments in particular generally increase, including as a result of the effects of those conditions on commercial real estate markets, the ability of commercial tenants to make loan payments, and the ability of a property to attract and retain commercial tenants. Investments that receive only the interest

portion or the principal portion of payments on the underlying assets may be highly volatile. Litigation with respect to the representations and warranties given in connection with the issuance of mortgage-backed securities can be an important consideration in investing in such securities, and the outcome of any such litigation could significantly impact the value of the Fund’s mortgage-backed investments.

Cash Position Risk If the Fund holds a significant portion of its assets in cash or cash equivalents, its investment returns may be adversely affected and the Fund may not achieve its investment objective.

Hedging Risk The Fund’s attempts at hedging and taking long and short positions in currencies may not be successful and could cause the Fund to lose money or fail to get the benefit of a gain on a hedged position. If expected changes to securities prices, interest rates, currency values, and exchange rates, or the creditworthiness of an issuer are not accurately predicted, the Fund could be in a worse position than if it had not entered into such transactions.

Leveraging Risk Instruments and transactions, including derivatives transactions, that create leverage may cause the value of an investment in the Fund to be more volatile, could result in larger losses than if they were not used, and tend to compound the effects of other risks.

Liquidity Risk Certain securities may be difficult (or impossible) to sell or certain positions may be difficult to close out at a desirable time and price, and the Fund may be required to hold an illiquid investment that is declining in value, or it may be required to sell certain illiquid investments at a price or time that is not advantageous in order to meet redemptions or other cash needs. Some securities may be subject to restrictions on resale. There can be no assurance that there will be a liquid market for instruments held by the Fund at any time. The Fund may not receive the proceeds from the sale of certain investments for an extended period.

Management and Operational Risk The Fund relies on the manager’s investment analysis and its selection of investments to achieve its investment objective, and the Fund is subject to the risk that the manager’s assessment of an investment is wrong. There can be no assurance that the Fund will achieve the intended results and the Fund may incur significant losses. The Fund also runs the

risk that deficiencies in the investment adviser’s, subadviser’s, or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

Market Risk The value of the Fund’s portfolio securities may decline, at times sharply and unpredictably, as a result of unfavorable market-induced changes affecting particular industries, sectors, or issuers. Stock and bond markets can decline significantly in response to issuer, market, economic, industry, political, regulatory, geopolitical, public health, and other conditions, as well as investor perceptions of these conditions. The Fund is subject to risks affecting issuers, such as management performance, financial leverage, industry problems, and reduced demand for goods or services.

Reinvestment Risk Income from the Fund’s portfolio will decline if and when the Fund invests the proceeds from matured, traded, or called debt obligations at market interest rates that are below the portfolio’s current earnings rate. A decline in income could affect the Fund’s overall return.

Repurchase Agreement Risk  These transactions must be fully collateralized, but involve credit risk to a Fund if the other party should default on its obligation and the Fund is delayed or prevented from recovering the collateral.

Risk of Investment in Other Funds or Pools The Fund is indirectly exposed to all of the risks of the underlying funds, including ETFs, in which it invests, including the risk that the underlying funds will not perform as expected. ETFs are subject to additional risks, including secondary market trading risks and the risk that an ETF’s shares may trade above or below net asset value. The Fund indirectly pays a portion of the expenses incurred by the underlying funds, which may, in the case of an ETF, include a portion of the expenses incurred below their net asset value.

Sector Risk The Fund may allocate more of its assets to particular industries or to particular economic, market, or industry sectors than to others. This could increase the volatility of the Fund’s portfolio, and the Fund’s performance may be more susceptible to developments affecting issuers in those industries or sectors than if the Fund invested more broadly.

Sovereign Debt Obligations Risk Investments in debt securities issued by governments or by government agencies and instrumentalities involve

the risk that the governmental entities responsible for repayment may be unable or unwilling to pay interest and repay principal when due. Many sovereign debt obligations may be rated below investment grade (“junk” or “high yield” bonds). Any restructuring of a sovereign debt obligation held by the Fund will likely have a significant adverse effect on the value of the obligation. In the event of default of sovereign debt, the Fund may be unable to pursue legal action against the sovereign issuer or to realize on collateral securing the debt.

U.S. Government Securities Risk Obligations of certain U.S. Government agencies and instrumentalities are not backed by the full faith and credit of the U.S. Government, and there can be no assurance that the U.S. Government would provide financial support to such agencies and instrumentalities.

Valuation Risk The Fund is subject to the risk of mispricing or improper valuation of its investments, in particular to the extent that its securities are fair valued.

When-Issued, Delayed Delivery, TBA, and Forward Commitment Transaction Risk These transactions may create leverage and involve a risk of loss if the value of the securities declines prior to settlement.

Performance Information

The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows changes in the Fund’s performance from year to year for Initial Class shares. The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare with those of a broad measure of market performance and an additional index that MML Advisers believes more closely reflects the market segments in which the Fund invests (Bloomberg U.S. Treasury Inflation Protected Securities (TIPS) Index (Series-L)). Performance shown does not reflect the fees and expenses deducted under the variable life insurance or variable annuity contract through which you invest in the Fund. If these amounts were reflected, returns would be less than those shown. Past performance is not necessarily an indication of how the Fund will perform in the future.

Annual Performance

Initial Class Shares

Average Annual Total Returns

(for the periods ended December 31, 2024)

​

(1)

Effective July 24, 2024, the Bloomberg U.S. Aggregate Bond Index replaced the Bloomberg U.S. Treasury Inflation Protected Securities (TIPS) Index (Series-L) as a broad measure of market performance in accordance with new regulatory disclosure requirements. The Fund continues to use the Bloomberg U.S. Treasury Inflation Protected Securities (TIPS) Index (Series-L) as a supplemental benchmark that MML Advisers believes more closely reflects the market segments in which the Fund invests.

​

MANAGEMENT

Investment Adviser: MML Investment Advisers, LLC (“MML Advisers”)

Subadviser(s): Barings LLC (“Barings”)

Sub-subadviser(s):  Baring International Investment Limited (“BIIL”)

Portfolio Manager(s):

Tom Duski  is a Managing Director and member of Barings’ Investment Grade Fixed Income Group. He has managed the Fund since April 2025.

Rishi Kapur, CFA is a Managing Director, member of Barings’ Private Placements &

Asset Based Finance Group, and Head of Barings’ Securitized Trading. He has managed the Fund since February 2025.

PURCHASE AND SALE OF FUND SHARES

Shares of the Fund are generally available to separate investment accounts of variable life insurance and variable annuity contracts offered by companies such as MassMutual. An investor should consult the company issuing the investor’s variable life insurance or variable annuity contract to determine how to make redemptions.

TAX INFORMATION

Dividends and capital gain distributions are paid to the insurance company separate accounts. Variable life insurance and variable annuity contract owners should refer to the variable life insurance or variable annuity product prospectus or consult with their own tax adviser for information regarding the tax consequences of their investment.

PAYMENTS TO INSURANCE COMPANIES AND THEIR AFFILIATES

The Fund is not sold directly to the general public but instead is offered as an underlying investment option for variable insurance contracts. The Fund and its related companies may make payments to the sponsoring insurance company (or its affiliates) or other intermediary for distribution and/or other services. These payments may be a factor that the insurance company considers in including the Fund as an underlying investment option in the variable insurance contract or may create a conflict of interest by influencing the insurance company or other intermediary to recommend the variable insurance contract over another investment. The prospectus (or other offering document) for your variable insurance contract may contain additional information about these payments.

INVESTMENT OBJECTIVE

This Fund seeks capital appreciation.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. The expenses in the table do not reflect deductions at the separate account level or contract level for any charges that may be incurred under a variable life insurance or variable annuity contract. If these charges were reflected, the fees and expenses in the table would be higher.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

​

(1)

Other expenses are based on estimated amounts for the current fiscal year of the Fund.

​

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in each share class of the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment earns a 5% return each year and that the Fund’s operating expenses are exactly as described in the preceding table. If separate account or variable life insurance or variable annuity contract expenses were included, overall expenses would be higher. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance.

INVESTMENTS, RISKS, AND PERFORMANCE​

Principal Investment Strategies

The Fund mainly invests in common stocks of “growth companies.” Growth companies are companies that the Fund’s subadviser, Invesco Advisers, Inc. (“Invesco Advisers”), expects to have above-average growth rates. Under normal circumstances, the Fund invests directly or indirectly at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in equity securities of large-cap companies. Equity securities may include common stocks, preferred stocks, securities convertible into common or preferred stock, rights, and warrants. Invesco Advisers currently defines “large-cap” companies as those that have a market capitalization, at the time of purchase, within the range of market capitalizations of the issuers included in the Russell 1000® Growth Index during the most recent 11-month period (based on month-end data) plus the most recent data during the current month (as of February 28, 2025, between $555.98 million and $2.89 trillion). This range is subject to change at any time due to market activity or changes in the composition of that index.

The Fund invests primarily in U.S. companies but may also purchase securities of issuers in any country, including developed countries and emerging markets (i.e., those that are generally in the early stages of their industrial cycle). The Fund has no limits on the amount of its assets that can be invested in foreign securities. Foreign securities are those of issuers that are organized under the laws of a foreign country or that have a substantial portion of their operations or assets in a foreign country or countries, or that derive a substantial portion of their revenue or profits from businesses, investments or sales outside of the United States, or whose “country of risk” is a foreign country as determined by a third party service provider. The Fund may at times have significant exposure to one or more industries or sectors. The Fund may hold a portion of its assets in cash or cash equivalents. The Fund is non-diversified, which means that it may hold larger positions in a smaller number of issuers than a diversified fund.

In selecting investments for the Fund, Invesco Advisers looks for companies with high growth potential using a “bottom-up” stock selection process. The “bottom-up” approach focuses on

fundamental analysis of individual issuers before considering the impact of overall economic, market, or industry trends. This approach includes analysis of a company’s financial statements and management structure and consideration of the company’s operations, product development, and its industry position. Invesco Advisers currently focuses on what it believes to be high-growth companies that are characterized by industry leadership, market share growth, high caliber management teams, sustainable competitive advantages, and strong growth themes or new innovative products or services. As reflected in the Fund’s name, Invesco Advisers’ “Discovery” team of portfolio managers seeks to discover such companies early. Invesco Advisers monitors individual issuers for changes in the factors above, which may trigger Invesco Advisers’ decision to sell a security, but does not require its decision to do so. The factors considered by Invesco Advisers may vary in particular cases and may change over time.

Principal Risks

The following are the Principal Risks of the Fund. The value of your investment in the Fund could go down as well as up. You can lose money by investing in the Fund. Certain risks relating to instruments and strategies used in the management of the Fund are placed first. The significance of any specific risk to an investment in the Fund will vary over time, depending on the composition of the Fund’s portfolio, market conditions, and other factors. You should read all of the risk information presented below carefully, because any one or more of these risks may result in losses to the Fund.

Equity Securities Risk Although stocks may have the potential to outperform other asset classes over the long term, their prices tend to fluctuate more dramatically over the shorter term. These movements may result from factors affecting individual companies, or from broader influences like changes in interest rates, market conditions, or investor confidence, or announcements of economic, political, or financial information.

Foreign Investment Risk; Emerging Markets Risk; Currency Risk Investments in securities of foreign issuers, securities of companies with significant foreign exposure, and foreign currencies can involve additional risks relating to market, industry, political, regulatory, public health, and other conditions. Political, social, diplomatic, and economic developments, U.S. and foreign

government action, or threat thereof, such as the imposition of currency or capital blockages, controls, or tariffs, economic and trade sanctions or embargoes, security trading suspensions, entering or exiting trade or other intergovernmental agreements, or the expropriation or nationalization of assets in a particular country, can cause dramatic declines in certain or all securities with exposure to that country and other countries. Sanctions, or the threat of sanctions, may cause volatility in regional and global markets and may negatively impact the performance of various sectors and industries, as well as companies in other countries, which could have a negative effect on the performance of the Fund. In the event of nationalization, expropriation, confiscation, or other government action, intervention, or restriction, the Fund could lose its entire investment in a particular foreign issuer or country. There may be quotas or other limits on the ability of the Fund (or clients of the Fund’s investment adviser or subadviser) to invest or maintain investments in securities of issuers in certain countries. Enforcing legal rights can be more difficult, costly, and limited in certain foreign countries and with respect to certain types of investments, and can be particularly difficult against foreign governments. Because non-U.S. securities are normally denominated and traded in currencies other than the U.S. dollar, the value of the Fund’s assets may be affected favorably or unfavorably by changes in currency exchange rates, exchange control regulations, and restrictions or prohibitions on the repatriation of non-U.S. currencies. Income and gains with respect to investments in certain countries may be subject to withholding and other taxes. There may be less information publicly available about a non-U.S. company than about a U.S. company, and many non-U.S. companies are not subject to accounting, auditing, and financial reporting standards, regulatory framework and practices comparable to those in the U.S. The securities of some non-U.S. companies, especially those in emerging markets, are less liquid and at times more volatile than securities of comparable U.S. companies. Emerging markets securities are subject to greater risks than securities issued in developed foreign markets, including less liquidity, less stringent investor protection and disclosure standards, less reliable settlement practices, greater price volatility, higher relative rates of inflation, greater political, economic, and social instability, greater custody and operational risks, greater risk of new or inconsistent government treatment of or

restrictions on issuers and instruments, and greater volatility in currency exchange rates, and are more susceptible to environmental problems. Many emerging market countries are highly reliant on international trade and exports, including the export of commodities. Their economies may be significantly impacted by fluctuations in commodity prices and the global demand for certain commodities. In addition, pandemics and outbreaks of contagious diseases may exacerbate pre-existing problems in emerging market countries with less established health care systems. Frontier markets, a subset of emerging markets, generally have smaller economies and less mature capital markets than emerging markets. As a result, the risks of investing in emerging market countries are magnified in frontier market countries. Frontier markets are more susceptible to having abrupt changes in currency values, less mature markets and settlement practices, and lower trading volumes that could lead to greater price volatility and illiquidity. Non-U.S. transaction costs, such as brokerage commissions and custody costs, may be higher than in the United States. In addition, foreign markets can react differently to market, economic, industry, political, regulatory, geopolitical, public health, and other conditions than the U.S. market. The Fund may invest in foreign securities known as depositary receipts. Investments in depositary receipts are subject to the same risks as direct investment in foreign securities, which include market, political, currency, and regulatory risks.

Growth Company Risk The prices of growth securities are often highly sensitive to market fluctuations because of their heavy dependence on future earnings or cash flow expectations, and can be more volatile than the market in general.

Large Company Risk Large-capitalization stocks as a group could fall out of favor with the market, causing the Fund’s investments in large-capitalization stocks to underperform investments that focus on small- or medium-capitalization stocks. Larger, more established companies may be slow to respond to challenges and may grow more slowly than smaller companies.

Small and Mid-Cap Company Risk Market risk and liquidity risk are particularly pronounced for securities of small and medium-sized companies, which may trade less frequently and in smaller volumes than more widely-held securities, and may fluctuate in price more than other securities. Their shares can be less liquid than those of larger

companies, especially during market declines. Small and medium-sized companies may have limited product lines, markets, or financial resources and may be dependent on a limited management group; they may have been recently organized and have little or no track record of success.

Cash Position Risk If the Fund holds a significant portion of its assets in cash or cash equivalents, its investment returns may be adversely affected and the Fund may not achieve its investment objective.

Convertible Securities Risk Convertible securities are subject to the risks of both debt instruments and equity securities. The price of a convertible security may change in response to changes in price of the underlying equity security, the credit quality of the issuer, and interest rates. In general, the values of convertible securities tend to decline as interest rates rise and to rise when interest rates fall. A convertible security generally has less potential for gain or loss than the underlying equity security.

Liquidity Risk Certain securities may be difficult (or impossible) to sell or certain positions may be difficult to close out at a desirable time and price, and the Fund may be required to hold an illiquid investment that is declining in value, or it may be required to sell certain illiquid investments at a price or time that is not advantageous in order to meet redemptions or other cash needs. Some securities may be subject to restrictions on resale. There can be no assurance that there will be a liquid market for instruments held by the Fund at any time. The Fund may not receive the proceeds from the sale of certain investments for an extended period.

Management and Operational Risk The Fund relies on the manager’s investment analysis and its selection of investments to achieve its investment objective, and the Fund is subject to the risk that the manager’s assessment of an investment is wrong. There can be no assurance that the Fund will achieve the intended results and the Fund may incur significant losses. The Fund also runs the risk that deficiencies in the investment adviser’s, subadviser’s, or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

Market Risk The value of the Fund’s portfolio securities may decline, at times sharply and unpredictably, as a result of unfavorable market-induced changes affecting particular industries, sectors, or issuers. Stock and bond markets can

decline significantly in response to issuer, market, economic, industry, political, regulatory, geopolitical, public health, and other conditions, as well as investor perceptions of these conditions. The Fund is subject to risks affecting issuers, such as management performance, financial leverage, industry problems, and reduced demand for goods or services.

Non-Diversification Risk Because the Fund may invest a relatively large percentage of its assets in a single issuer or small number of issuers than a diversified fund, the Fund’s performance could be closely tied to the value of one issuer or a small number of issuers and could be more volatile than the performance of a diversified fund.

Preferred Stock Risk Like other equity securities, preferred stock is subject to the risk that its value may decrease based on actual or perceived changes in the business or financial condition of the issuer. In addition, changes in interest rates may adversely affect the value of a preferred stock that pays a fixed dividend. Preferred stocks are also subject to additional risks, such as potentially greater volatility and risks related to deferral, non-cumulative dividends, subordination, liquidity, limited voting rights, and special redemption rights.

Sector Risk The Fund may allocate more of its assets to particular industries or to particular economic, market, or industry sectors than to others. This could increase the volatility of the Fund’s portfolio, and the Fund’s performance may be more susceptible to developments affecting issuers in those industries or sectors than if the Fund invested more broadly.

Valuation Risk The Fund is subject to the risk of mispricing or improper valuation of its investments, in particular to the extent that its securities are fair valued.

Performance Information

The Fund had not begun operations prior to the date of this Prospectus, and therefore has no performance history. Because the Fund is new, there is no table which shows how the Fund’s returns have deviated from the broad market. Performance history for the Fund, along with the performance of the S&P 500® Index as a primary index and the Russell 1000 Growth Index as a secondary index, will be available after the Fund has been in operation for one calendar year.

MANAGEMENT

Investment Adviser: MML Investment Advisers, LLC (“MML Advisers”)

Subadviser(s): Invesco Advisers, Inc. (“Invesco Advisers”)

Portfolio Manager(s):

Ash Shah, CFA is a Portfolio Manager at Invesco Advisers. He has managed the Fund since its inception (April 2025).

Ronald Zibelli, Jr., CFA is a Portfolio Manager at Invesco Advisers. He has managed the Fund since its inception (April 2025).

PURCHASE AND SALE OF FUND SHARES

Shares of the Fund are generally available to separate investment accounts of variable life insurance and variable annuity contracts offered by companies such as MassMutual. An investor should consult the company issuing the investor’s variable life insurance or variable annuity contract to determine how to make redemptions.

TAX INFORMATION

Dividends and capital gain distributions are paid to the insurance company separate accounts. Variable life insurance and variable annuity contract owners should refer to the variable life insurance or variable annuity product prospectus or consult with their own tax adviser for information regarding the tax consequences of their investment.

PAYMENTS TO INSURANCE COMPANIES AND THEIR AFFILIATES

The Fund is not sold directly to the general public but instead is offered as an underlying investment option for variable insurance contracts. The Fund and its related companies may make payments to the sponsoring insurance company (or its affiliates) or other intermediary for distribution and/or other services. These payments may be a factor that the insurance company considers in including the Fund as an underlying investment option in the variable insurance contract or may create a conflict of interest by influencing the insurance company or other intermediary to recommend the variable insurance contract over another investment. The prospectus (or other offering document) for your variable insurance contract may contain additional information about these payments.

INVESTMENT OBJECTIVE

This Fund seeks capital appreciation.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. The expenses in the table do not reflect deductions at the separate account level or contract level for any charges that may be incurred under a variable life insurance or variable annuity contract. If these charges were reflected, the fees and expenses in the table would be higher.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

​

(1)

Other expenses are based on estimated amounts for the current fiscal year of the Fund.

​

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in each share class of the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment earns a 5% return each year and that the Fund’s operating expenses are exactly as described in the preceding table. If separate account or variable life insurance or variable annuity contract expenses were included, overall expenses would be higher. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance.

INVESTMENTS, RISKS, AND PERFORMANCE​

Principal Investment Strategies

The Fund mainly invests in common stocks of U.S. companies that the Fund’s subadviser, Invesco Advisers, Inc. (“Invesco Advisers”), expects to have above-average growth rates. The Fund seeks to invest in newer companies or in more established companies that are in the early growth phase of their business cycle, which is typically marked by above-average growth rates. Under normal circumstances, the Fund invests directly or indirectly at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in equity securities of mid-cap companies. Equity securities may include common stocks, preferred stocks, securities convertible into common or preferred stock, rights, and warrants. Invesco Advisers currently defines “mid-cap” companies as those that have a market capitalization, at the time of purchase, within the range of market capitalizations of the issuers included in the Russell Midcap® Growth Index during the most recent 11-month period (based on month-end data) plus the most recent data during the current month (as of February 28, 2025, between $555.98 million and $82.33 billion). This range is subject to change at any time due to market activity or changes in the composition of that index. The Fund may invest up to 20% of its net assets in companies whose market capitalizations at the time of investment are outside of that capitalization range.

The Fund invests primarily in U.S. companies but may also purchase securities of issuers in any country, including developed countries and emerging markets (i.e., those that are generally in the early stages of their industrial cycle). The Fund has no limits on the amount of its assets that can be invested in foreign securities, but currently does not intend to invest substantially in such securities. Foreign securities are those of issuers that are organized under the laws of a foreign country or that have a substantial portion of their operations or assets in a foreign country or countries, or that derive a substantial portion of their revenue or profits from businesses, investments or sales outside of the United States, or whose “country of risk” is a foreign country as determined by a third-party service provider. The Fund may at times have significant exposure to one or more industries or sectors. The Fund may hold a portion of its assets in cash or cash equivalents.

In selecting investments for the Fund, Invesco Advisers looks for companies with high growth potential using a “bottom-up” stock selection process. The “bottom-up” approach focuses on fundamental analysis of individual issuers before considering the impact of overall economic, market, or industry trends. This approach includes analysis of a company’s financial statements and management structure and consideration of the company’s operations, product development, and its industry position. Invesco Advisers currently focuses on what it believes to be high-growth companies that are characterized by industry leadership, market share growth, high caliber management teams, sustainable competitive advantages, and strong growth themes or new innovative products or services. As reflected in the Fund’s name, Invesco Advisers’ “Discovery” team of portfolio managers seeks to discover such companies early. Invesco Advisers monitors individual issuers for changes in the factors above, which may trigger Invesco Advisers’ decision to sell a security, but does not require its decision to do so. The factors considered by Invesco Advisers may vary in particular cases and may change over time.

The Fund expects that it will engage in active and frequent trading and so will typically have a relatively high portfolio turnover rate.

Principal Risks

The following are the Principal Risks of the Fund. The value of your investment in the Fund could go down as well as up. You can lose money by investing in the Fund. Certain risks relating to instruments and strategies used in the management of the Fund are placed first. The significance of any specific risk to an investment in the Fund will vary over time, depending on the composition of the Fund’s portfolio, market conditions, and other factors. You should read all of the risk information presented below carefully, because any one or more of these risks may result in losses to the Fund.

Equity Securities Risk Although stocks may have the potential to outperform other asset classes over the long term, their prices tend to fluctuate more dramatically over the shorter term. These movements may result from factors affecting individual companies, or from broader influences like changes in interest rates, market conditions, or investor confidence, or announcements of economic, political, or financial information.

Small and Mid-Cap Company Risk Market risk and liquidity risk are particularly pronounced for

securities of small and medium-sized companies, which may trade less frequently and in smaller volumes than more widely-held securities, and may fluctuate in price more than other securities. Their shares can be less liquid than those of larger companies, especially during market declines. Small and medium-sized companies may have limited product lines, markets, or financial resources and may be dependent on a limited management group; they may have been recently organized and have little or no track record of success.

Foreign Investment Risk; Emerging Markets Risk; Currency Risk Investments in securities of foreign issuers, securities of companies with significant foreign exposure, and foreign currencies can involve additional risks relating to market, industry, political, regulatory, public health, and other conditions. Political, social, diplomatic, and economic developments, U.S. and foreign government action, or threat thereof, such as the imposition of currency or capital blockages, controls, or tariffs, economic and trade sanctions or embargoes, security trading suspensions, entering or exiting trade or other intergovernmental agreements, or the expropriation or nationalization of assets in a particular country, can cause dramatic declines in certain or all securities with exposure to that country and other countries. Sanctions, or the threat of sanctions, may cause volatility in regional and global markets and may negatively impact the performance of various sectors and industries, as well as companies in other countries, which could have a negative effect on the performance of the Fund. In the event of nationalization, expropriation, confiscation, or other government action, intervention, or restriction, the Fund could lose its entire investment in a particular foreign issuer or country. There may be quotas or other limits on the ability of the Fund (or clients of the Fund’s investment adviser or subadviser) to invest or maintain investments in securities of issuers in certain countries. Enforcing legal rights can be more difficult, costly, and limited in certain foreign countries and with respect to certain types of investments, and can be particularly difficult against foreign governments. Because non-U.S. securities are normally denominated and traded in currencies other than the U.S. dollar, the value of the Fund’s assets may be affected favorably or unfavorably by changes in currency exchange rates, exchange control regulations, and restrictions or prohibitions on the repatriation of non-U.S. currencies. Income and gains with respect to investments in certain countries may be subject to

withholding and other taxes. There may be less information publicly available about a non-U.S. company than about a U.S. company, and many non-U.S. companies are not subject to accounting, auditing, and financial reporting standards, regulatory framework and practices comparable to those in the U.S. The securities of some non-U.S. companies, especially those in emerging markets, are less liquid and at times more volatile than securities of comparable U.S. companies. Emerging markets securities are subject to greater risks than securities issued in developed foreign markets, including less liquidity, less stringent investor protection and disclosure standards, less reliable settlement practices, greater price volatility, higher relative rates of inflation, greater political, economic, and social instability, greater custody and operational risks, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater volatility in currency exchange rates, and are more susceptible to environmental problems. Many emerging market countries are highly reliant on international trade and exports, including the export of commodities. Their economies may be significantly impacted by fluctuations in commodity prices and the global demand for certain commodities. In addition, pandemics and outbreaks of contagious diseases may exacerbate pre-existing problems in emerging market countries with less established health care systems. Frontier markets, a subset of emerging markets, generally have smaller economies and less mature capital markets than emerging markets. As a result, the risks of investing in emerging market countries are magnified in frontier market countries. Frontier markets are more susceptible to having abrupt changes in currency values, less mature markets and settlement practices, and lower trading volumes that could lead to greater price volatility and illiquidity. Non-U.S. transaction costs, such as brokerage commissions and custody costs, may be higher than in the United States. In addition, foreign markets can react differently to market, economic, industry, political, regulatory, geopolitical, public health, and other conditions than the U.S. market. The Fund may invest in foreign securities known as depositary receipts. Investments in depositary receipts are subject to the same risks as direct investment in foreign securities, which include market, political, currency, and regulatory risks.

Growth Company Risk The prices of growth securities are often highly sensitive to market fluctuations because of their heavy dependence on

future earnings or cash flow expectations, and can be more volatile than the market in general.

Cash Position Risk If the Fund holds a significant portion of its assets in cash or cash equivalents, its investment returns may be adversely affected and the Fund may not achieve its investment objective.

Convertible Securities Risk Convertible securities are subject to the risks of both debt instruments and equity securities. The price of a convertible security may change in response to changes in price of the underlying equity security, the credit quality of the issuer, and interest rates. In general, the values of convertible securities tend to decline as interest rates rise and to rise when interest rates fall. A convertible security generally has less potential for gain or loss than the underlying equity security.

Frequent Trading/Portfolio Turnover Risk Portfolio turnover generally involves some expense to the Fund. The trading costs associated with portfolio turnover may adversely affect the Fund’s performance.

Liquidity Risk Certain securities may be difficult (or impossible) to sell or certain positions may be difficult to close out at a desirable time and price, and the Fund may be required to hold an illiquid investment that is declining in value, or it may be required to sell certain illiquid investments at a price or time that is not advantageous in order to meet redemptions or other cash needs. Some securities may be subject to restrictions on resale. There can be no assurance that there will be a liquid market for instruments held by the Fund at any time. The Fund may not receive the proceeds from the sale of certain investments for an extended period.

Management and Operational Risk The Fund relies on the manager’s investment analysis and its selection of investments to achieve its investment objective, and the Fund is subject to the risk that the manager’s assessment of an investment is wrong. There can be no assurance that the Fund will achieve the intended results and the Fund may incur significant losses. The Fund also runs the risk that deficiencies in the investment adviser’s, subadviser’s, or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

Market Risk The value of the Fund’s portfolio securities may decline, at times sharply and unpredictably, as a result of unfavorable market-induced changes affecting particular industries,

sectors, or issuers. Stock and bond markets can decline significantly in response to issuer, market, economic, industry, political, regulatory, geopolitical, public health, and other conditions, as well as investor perceptions of these conditions. The Fund is subject to risks affecting issuers, such as management performance, financial leverage, industry problems, and reduced demand for goods or services.

Preferred Stock Risk Like other equity securities, preferred stock is subject to the risk that its value may decrease based on actual or perceived changes in the business or financial condition of the issuer. In addition, changes in interest rates may adversely affect the value of a preferred stock that pays a fixed dividend. Preferred stocks are also subject to additional risks, such as potentially greater volatility and risks related to deferral, non-cumulative dividends, subordination, liquidity, limited voting rights, and special redemption rights.

Sector Risk The Fund may allocate more of its assets to particular industries or to particular economic, market, or industry sectors than to others. This could increase the volatility of the Fund’s portfolio, and the Fund’s performance may be more susceptible to developments affecting issuers in those industries or sectors than if the Fund invested more broadly.

Valuation Risk The Fund is subject to the risk of mispricing or improper valuation of its investments, in particular to the extent that its securities are fair valued.

Performance Information

The Fund had not begun operations prior to the date of this Prospectus, and therefore has no performance history. Because the Fund is new, there is no table which shows how the Fund’s returns have deviated from the broad market. Performance history for the Fund, along with the performance of the Russell 3000® Index as a primary index and the Russell Midcap Growth Index as a secondary index, will be available after the Fund has been in operation for one calendar year.

MANAGEMENT

Investment Adviser: MML Investment Advisers, LLC (“MML Advisers”)

Subadviser(s): Invesco Advisers, Inc. (“Invesco Advisers”)

Portfolio Manager(s):

Justin Livengood, CFA is a Portfolio Manager at Invesco Advisers. He has managed the Fund since its inception (April 2025).

Ronald Zibelli, Jr., CFA is a Portfolio Manager at Invesco Advisers. He has managed the Fund since its inception (April 2025).

PURCHASE AND SALE OF FUND SHARES

Shares of the Fund are generally available to separate investment accounts of variable life insurance and variable annuity contracts offered by companies such as MassMutual. An investor should consult the company issuing the investor’s variable life insurance or variable annuity contract to determine how to make redemptions.

TAX INFORMATION

Dividends and capital gain distributions are paid to the insurance company separate accounts. Variable life insurance and variable annuity contract owners should refer to the variable life insurance or variable annuity product prospectus or consult with their own tax adviser for information regarding the tax consequences of their investment.

PAYMENTS TO INSURANCE COMPANIES AND THEIR AFFILIATES

The Fund is not sold directly to the general public but instead is offered as an underlying investment option for variable insurance contracts. The Fund and its related companies may make payments to the sponsoring insurance company (or its affiliates) or other intermediary for distribution and/or other services. These payments may be a factor that the insurance company considers in including the Fund as an underlying investment option in the variable insurance contract or may create a conflict of interest by influencing the insurance company or other intermediary to recommend the variable insurance contract over another investment. The prospectus (or other offering document) for your variable insurance contract may contain additional information about these payments.

INVESTMENT OBJECTIVE

The Fund seeks to achieve as high a total return over time as is considered consistent with prudent investment risk, preservation of capital and recognition of the Fund’s stated asset allocation.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. The expenses in the table do not reflect deductions at the separate account level or contract level for any charges that may be incurred under a variable life insurance or variable annuity contract. If these charges were reflected, the fees and expenses in the table would be higher.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

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(1)

Because Total Annual Fund Operating Expenses include Acquired Fund Fees and Expenses, they may not correspond to the ratios of expenses to average daily net assets shown in the “Financial Highlights” tables in the Prospectus, which reflect the operating expenses of the Fund and do not include Acquired Fund Fees and Expenses.

​

(2)

The expenses in the above table reflect a written agreement by MML Advisers to cap the fees and expenses of the Fund (other than extraordinary legal and other expenses, interest expense, expenses related to borrowings, securities lending, leverage, taxes, and brokerage, short sale dividend and loan expense, or other non-recurring or unusual expenses such as organizational expenses and shareholder meeting expenses, as applicable) through April 30, 2026, to the extent that Total Annual Fund Operating Expenses after Expense Reimbursement would otherwise exceed 0.50% and 0.75% for Class II and Service Class I shares, respectively. The Total Annual Fund Operating Expenses after Expense Reimbursement shown in the above table may exceed these amounts, because, as noted in the previous sentence, certain fees and expenses are excluded from the cap. The agreement can only be terminated by mutual consent of the Board of Trustees on behalf of the Fund and MML Advisers.

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Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that

you invest $10,000 in each share class of the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment earns a 5% return each year and that the Fund’s operating expenses are exactly as described in the preceding table. If separate account or variable life insurance or variable annuity contract expenses were included, overall expenses would be higher. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 7% of the average value of its portfolio.

INVESTMENTS, RISKS, AND PERFORMANCE​

Principal Investment Strategies

The Fund is a “fund of funds” that seeks to achieve its investment objective by allocating substantially all of its assets among exchange-traded funds (“ETFs”) providing exposures to various asset classes. The Fund’s investment adviser, MML Investment Advisers, LLC (“MML Advisers”), determines the Fund’s asset allocation strategy and implements this strategy by selecting ETFs for investment and determining the amounts of the Fund’s assets to be invested in each. The ETFs MML Advisers will consider for investment by the Fund will provide exposures to equity securities or to fixed-income securities. BlackRock Investment Management, LLC (“BlackRock”) is the Fund’s subadviser, and is responsible solely for the trading and execution of MML Advisers’ investment and allocation decisions. Under normal circumstances, the Fund invests at least 80% (and, typically, substantially all) of its net assets (plus the amount of any borrowings for investment purposes) in

iShares® ETFs*. iShares ETFs are advised by an affiliate of BlackRock.

The Fund typically invests approximately 60% of its net assets in equity ETFs and approximately 40% of its net assets in fixed income ETFs. Equity ETFs may include funds that provide exposures to, among other things, domestic and international equity securities, including common stocks, preferred stocks, securities convertible into common or preferred stock, rights, and warrants, of issuers of any size, as well as real estate investment trusts (“REITs”). Fixed income ETFs may include funds that provide exposures to, among other things, domestic and non-U.S. bonds, U.S. Government securities, non-U.S. sovereign obligations, mortgage-backed securities, securities below investment grade (“junk” or “high yield” bonds, including securities in default), inflation-protected securities, bank loans, and cash or money market instruments.

The Fund’s equity allocation may include equity exposures chosen by reference to, for example, style (including both value and growth funds), market capitalization (including both large-cap and small-cap funds), global investments (including domestic and international (including emerging market) funds), or other factors. The Fund’s fixed-income allocation may include exposures chosen by reference to, for example, sector (including government, corporate, agency, mortgage-backed securities, and other sectors), duration (a calculation of the average life of a bond which measures its price risk), credit quality (including securities below investment grade (“junk” or “high yield” bonds, including securities in default)), geographic location, or other factors. The percentage allocation to the various types of equity and fixed-income securities are determined at the discretion of MML Advisers.

MML Advisers will typically rebalance to these strategic targets on a quarterly basis. MML Advisers may at any time reassess and make revisions in the Fund’s asset allocation strategy consistent with the Fund’s investment objective and strategy, including revising the weightings among the investments described above and adding or removing ETFs from the asset allocation strategy. Actual allocations between equity and fixed income investments will typically not vary from the Fund’s target asset allocations by more than 10%, although MML Advisers may determine in light

*

iShares® and BlackRock® are registered trademarks of BlackRock, Inc. and its affiliates and are used under license.

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of market conditions or other factors that a greater variation is warranted to protect the Fund or achieve its investment goal. BlackRock will place, and oversee the execution of, trades as directed by MML Advisers to implement the asset allocation strategy.

ETFs in which the Fund invests may use derivatives contracts to achieve their investment objectives. Use of derivatives by an ETF may create investment leverage.

An ETF may enter into dollar roll or reverse repurchase agreement transactions. Some investments by an ETF may be restricted as to resale or otherwise considered to be illiquid. The Fund or an ETF may enter into repurchase agreement transactions. The Fund will bear a pro rata share of the ETFs’ expenses. The Fund also bears all of the risks associated with the investment strategies used by the ETFs.

Through its investments in ETFs, the Fund may at times have significant exposure to one or more industries or sectors. The Fund may hold a portion of its assets in cash or cash equivalents. A description of the ETFs in which the Fund expects to invest is included in Appendix D of the Statement of Additional Information (“SAI”).

Because the Fund will invest substantially all of its assets in ETFs advised by an affiliate of BlackRock, the Fund will not invest in ETFs advised or sponsored by others, even if they are less expensive or have better historical performance records. BlackRock does not receive a subadvisory fee for its services; it does, however, receive fees from the ETFs in which the Fund invests. MML Advisers might be seen to be subject to a conflict of interest, having an interest in selecting ETFs to provide an appropriate level of revenue or other benefits to BlackRock. MML Advisers has advised the Fund that, as a fiduciary to the Fund, MML Advisers has a duty to put the best interests of the Fund ahead of its own interest and that, consequently, it will make investment decisions for the Fund in the best interest of the Fund to achieve the Fund’s investment objectives and not for the benefit of MML Advisers, without regard to any benefit to BlackRock from the selection of different ETFs.

Principal Risks

The following are the Principal Risks of the Fund. The value of your investment in the Fund could go down as well as up. You can lose money by investing in the Fund. Although the descriptions

below refer to the risks relating to investment activities of the Fund, many of the risks arise due to the investment activities of the ETFs in which it invests. Certain risks relating to instruments and strategies used in the management of the Fund are placed first. The significance of any specific risk to an investment in the Fund will vary over time, depending on the composition of the Fund’s portfolio, market conditions, and other factors. You should read all of the risk information presented below carefully, because any one or more of these risks may result in losses to the Fund.

Allocation Risk There is no assurance that allocation decisions will result in the desired performance effects. There is a risk that MML Advisers’ evaluations and assumptions regarding asset classes or ETFs may be incorrect in view of actual market conditions. The requirement that substantially all of the Fund’s assets be invested in ETFs advised by an affiliate of BlackRock as noted in “Principal Investment Strategies” may adversely affect Fund performance.

Risk of Investment in Other Funds or Pools The Fund is indirectly exposed to all of the risks of the underlying funds, including ETFs, in which it invests, including the risk that the underlying funds will not perform as expected. ETFs are subject to additional risks, including secondary market trading risks and the risk that an ETF’s shares may trade above or below net asset value. The Fund indirectly pays a portion of the expenses incurred by the underlying funds, which may, in the case of an ETF, include a portion of the expenses incurred below their net asset value.

Bank Loans Risk Many of the risks associated with bank loans are similar to the risks of investing in below investment grade debt securities. Changes in the financial condition of the borrower or economic conditions or other circumstances may reduce the capacity of the borrower to make principal and interest payments on such instruments and may lead to defaults. Senior secured bank loans are typically supported by collateral; however the value of the collateral may be insufficient to cover the amount owed to the Fund, or the Fund may be prevented or delayed from realizing on the collateral. Some loans may be unsecured; unsecured loans generally present a greater risk of loss to the Fund if the issuer defaults. If the Fund relies on a third party to administer a loan, the Fund is subject to the risk that the third party will fail to perform its obligations. In addition, if the Fund holds only a

participation interest in a loan made by a third party, the Fund’s receipt of payments on the loan will depend on the third party’s willingness and ability to make those payments to the Fund. The settlement time for certain loans is longer than the settlement time for many other types of investments, and the Fund may not receive the payment for a loan sold by it until well after the sale; that cash would be unavailable for payment of redemption proceeds or for reinvestment. Interests in some bank loans may not be readily marketable and may be subject to restrictions on resale. In some cases, negotiations involved in disposing of indebtedness may require weeks to complete. Consequently, some indebtedness may be difficult or impossible to dispose of readily at what the Fund believes to be a fair price. Some loans may not be considered “securities” for certain purposes under the federal securities laws, and purchasers, such as the Fund, therefore may not be entitled to rely on the anti-fraud protections of the federal securities laws.

Below Investment Grade Debt Securities Risk Below investment grade debt securities, commonly known as “junk” or “high yield” bonds, have speculative characteristics and involve greater volatility of price and yield, greater risk of loss of principal and interest, and generally reflect a greater possibility of an adverse change in financial condition that could affect an issuer’s ability to honor its obligations.

Cash Position Risk If the Fund holds a significant portion of its assets in cash or cash equivalents, its investment returns may be adversely affected and the Fund may not achieve its investment objective.

Convertible Securities Risk Convertible securities are subject to the risks of both debt instruments and equity securities. The price of a convertible security may change in response to changes in price of the underlying equity security, the credit quality of the issuer, and interest rates. In general, the values of convertible securities tend to decline as interest rates rise and to rise when interest rates fall. A convertible security generally has less potential for gain or loss than the underlying equity security.

Credit Risk Credit risk is the risk that an issuer, guarantor, or liquidity provider of a fixed income security held by the Fund may be unable or unwilling, or may be perceived (whether by market participants, ratings agencies, pricing services or otherwise) as unable or unwilling, to make timely principal and/or interest payments, or to otherwise

honor its obligations. The Fund may also be exposed to the credit risk of its counterparty to repurchase agreements, reverse repurchase agreements, swap transactions, and other derivatives transactions, and to the counterparty’s ability or willingness to perform in accordance with the terms of the transaction. The value of such transactions to the Fund will depend on the willingness and ability of the counterparty to perform its obligations, including among other things the obligation to return collateral or margin to the Fund. If a counterparty becomes bankrupt or otherwise fails to perform its obligations under a derivative contract due to financial difficulties, the Fund may experience significant delays in obtaining any recovery under the derivative contract in a bankruptcy or other reorganization proceeding. The Fund may obtain only a limited recovery or may obtain no recovery in such circumstances.

Defaulted and Distressed Securities Risk Because the issuer of such securities is in default and is likely to be in distressed financial condition, repayment of defaulted securities and obligations of distressed issuers (including insolvent issuers or issuers in payment or covenant default, in workout or restructuring, or in bankruptcy or insolvency proceedings) is uncertain. To the extent the Fund is invested in distressed securities, its ability to achieve current income for its shareholders may be diminished.

Derivatives Risk Derivatives can be highly volatile and involve risks different from, and potentially greater than, direct investments, including risks of imperfect correlation between the value of derivatives and underlying assets, counterparty default, potential losses that partially or completely offset gains, and illiquidity. Derivatives can create investment leverage. Losses from derivatives can be substantially greater than the derivatives’ original cost and can sometimes be unlimited. If the value of a derivative does not correlate well with the particular market or asset class the derivative is designed to provide exposure to, the derivative may not have the effect or benefit anticipated. Derivatives can also reduce the opportunity for gains or result in losses by offsetting positive returns in other investments. Many derivatives are traded in the over-the-counter market and not on exchanges.

Dollar Roll and Reverse Repurchase Agreement Transaction Risk These transactions generally create leverage and subject the Fund to the credit risk of the counterparty.

Equity Securities Risk Although stocks may have the potential to outperform other asset classes over the long term, their prices tend to fluctuate more dramatically over the shorter term. These movements may result from factors affecting individual companies, or from broader influences like changes in interest rates, market conditions, or investor confidence, or announcements of economic, political, or financial information.

Fixed Income Securities Risk The values of fixed income securities typically will decline during periods of rising interest rates, and can also decline in response to changes in the financial condition of the issuer, borrower, counterparty, or underlying collateral assets, or changes in market, economic, industry, political, regulatory, public health, and other conditions affecting a particular type of security or issuer or fixed income securities generally. Certain events, such as market or economic developments, regulatory or government actions, natural disasters, pandemics, terrorist attacks, war, and other geopolitical events can have a dramatic adverse effect on the debt market and the overall liquidity of the market for fixed income securities. During those periods, the Fund may experience high levels of shareholder redemptions, and may have to sell securities at times when the Fund would otherwise not do so, and potentially at unfavorable prices. Certain securities may be difficult to value during such periods. Fixed income securities are subject to interest rate risk (the risk that the value of a fixed income security will fall when interest rates rise), extension risk (the risk that the average life of a security will be extended through a slowing of principal payments), prepayment risk (the risk that a security will be prepaid and the Fund will be required to reinvest at a less favorable rate), duration risk (the risk that longer-term securities may be more sensitive to interest rate changes), inflation risk (the risk that as inflation increases, the present value of the Fund’s fixed income investment typically will decline), and credit risk.

Foreign Investment Risk; Emerging Markets Risk; Currency Risk Investments in securities of foreign issuers, securities of companies with significant foreign exposure, and foreign currencies can involve additional risks relating to market, industry, political, regulatory, public health, and other conditions. Political, social, diplomatic, and economic developments, U.S. and foreign government action, or threat thereof, such as the imposition of currency or capital blockages, controls, or tariffs, economic and trade sanctions

or embargoes, security trading suspensions, entering or exiting trade or other intergovernmental agreements, or the expropriation or nationalization of assets in a particular country, can cause dramatic declines in certain or all securities with exposure to that country and other countries. Sanctions, or the threat of sanctions, may cause volatility in regional and global markets and may negatively impact the performance of various sectors and industries, as well as companies in other countries, which could have a negative effect on the performance of the Fund. In the event of nationalization, expropriation, confiscation, or other government action, intervention, or restriction, the Fund could lose its entire investment in a particular foreign issuer or country. There may be quotas or other limits on the ability of the Fund (or clients of the Fund’s investment adviser or subadviser) to invest or maintain investments in securities of issuers in certain countries. Enforcing legal rights can be more difficult, costly, and limited in certain foreign countries and with respect to certain types of investments, and can be particularly difficult against foreign governments. Because non-U.S. securities are normally denominated and traded in currencies other than the U.S. dollar, the value of the Fund’s assets may be affected favorably or unfavorably by changes in currency exchange rates, exchange control regulations, and restrictions or prohibitions on the repatriation of non-U.S. currencies. Income and gains with respect to investments in certain countries may be subject to withholding and other taxes. There may be less information publicly available about a non-U.S. company than about a U.S. company, and many non-U.S. companies are not subject to accounting, auditing, and financial reporting standards, regulatory framework and practices comparable to those in the U.S. The securities of some non-U.S. companies, especially those in emerging markets, are less liquid and at times more volatile than securities of comparable U.S. companies. Emerging markets securities are subject to greater risks than securities issued in developed foreign markets, including less liquidity, less stringent investor protection and disclosure standards, less reliable settlement practices, greater price volatility, higher relative rates of inflation, greater political, economic, and social instability, greater custody and operational risks, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater volatility in currency exchange rates, and are more susceptible to environmental problems. Many

emerging market countries are highly reliant on international trade and exports, including the export of commodities. Their economies may be significantly impacted by fluctuations in commodity prices and the global demand for certain commodities. In addition, pandemics and outbreaks of contagious diseases may exacerbate pre-existing problems in emerging market countries with less established health care systems. Frontier markets, a subset of emerging markets, generally have smaller economies and less mature capital markets than emerging markets. As a result, the risks of investing in emerging market countries are magnified in frontier market countries. Frontier markets are more susceptible to having abrupt changes in currency values, less mature markets and settlement practices, and lower trading volumes that could lead to greater price volatility and illiquidity. Non-U.S. transaction costs, such as brokerage commissions and custody costs, may be higher than in the United States. In addition, foreign markets can react differently to market, economic, industry, political, regulatory, geopolitical, public health, and other conditions than the U.S. market. The Fund may invest in foreign securities known as depositary receipts. Investments in depositary receipts are subject to the same risks as direct investment in foreign securities, which include market, political, currency, and regulatory risks.

Geographic Focus Risk When the Fund focuses investments on a particular country, group of countries, or geographic region, its performance will be closely tied to the market, currency, economic, political, or regulatory conditions and developments in those countries or that region, and could be more volatile than the performance of more geographically diversified funds.

Growth Company Risk The prices of growth securities are often highly sensitive to market fluctuations because of their heavy dependence on future earnings or cash flow expectations, and can be more volatile than the market in general.

Hedging Risk The Fund’s attempts at hedging and taking long and short positions in currencies may not be successful and could cause the Fund to lose money or fail to get the benefit of a gain on a hedged position. If expected changes to securities prices, interest rates, currency values, and exchange rates, or the creditworthiness of an issuer are not accurately predicted, the Fund could be in a worse position than if it had not entered into such transactions.

Index Funds Risk Certain ETFs may attempt to track the performance of a specified index. Therefore, securities may be purchased, retained, and sold by the ETF at times when an actively managed fund would not do so. The structure and composition of the index will affect the performance, volatility, and risk of the index and, consequently, the performance, volatility, and risk of the ETF. While the investment adviser or subadviser seeks to track the performance of the index (i.e., achieve a high degree of correlation with the index), the ETF’s return may not match the return of the index. The ETF incurs a number of operating expenses not applicable to the index, and may incur costs in buying and selling securities. In addition, the ETF may not be fully invested at times, generally as a result of cash flows into or out of the ETF.

Inflation-Linked Securities Risk Such securities may change in value in response to actual or anticipated changes in inflation rates in a manner unanticipated by the Fund’s portfolio manager or investors generally. Inflation-linked securities are subject to fixed income securities risks. When inflation is low, declining, or negative, the Fund’s performance could lag the performance of more conventional bond funds. Inflation rates may change frequently and drastically as a result of various factors, including unexpected shifts in the domestic or global economy (or expectations that such policies will change), and the Fund’s investments may not keep pace with inflation, which may result in losses to the Fund’s investors.

Large Company Risk Large-capitalization stocks as a group could fall out of favor with the market, causing the Fund’s investments in large-capitalization stocks to underperform investments that focus on small- or medium-capitalization stocks. Larger, more established companies may be slow to respond to challenges and may grow more slowly than smaller companies.

Leveraging Risk Instruments and transactions, including derivatives, dollar roll, and reverse repurchase agreement transactions, that create leverage may cause the value of an investment in the Fund to be more volatile, could result in larger losses than if they were not used, and tend to compound the effects of other risks.

Liquidity Risk Certain securities may be difficult (or impossible) to sell or certain positions may be difficult to close out at a desirable time and price, and the Fund may be required to hold an illiquid investment that is declining in value, or it may

be required to sell certain illiquid investments at a price or time that is not advantageous in order to meet redemptions or other cash needs. Some securities may be subject to restrictions on resale. There can be no assurance that there will be a liquid market for instruments held by the Fund at any time. The Fund may not receive the proceeds from the sale of certain investments for an extended period.

Management and Operational Risk The Fund relies on the manager’s investment analysis and its selection of investments to achieve its investment objective, and the Fund is subject to the risk that the manager’s assessment of an investment is wrong. There can be no assurance that the Fund will achieve the intended results and the Fund may incur significant losses. The Fund also runs the risk that deficiencies in the investment adviser’s, subadviser’s, or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

Market Risk The value of the Fund’s portfolio securities may decline, at times sharply and unpredictably, as a result of unfavorable market-induced changes affecting particular industries, sectors, or issuers. Stock and bond markets can decline significantly in response to issuer, market, economic, industry, political, regulatory, geopolitical, public health, and other conditions, as well as investor perceptions of these conditions. The Fund is subject to risks affecting issuers, such as management performance, financial leverage, industry problems, and reduced demand for goods or services.

Mortgage- and Asset-Backed Securities Risk Investments in mortgage- and asset-backed securities subject the Fund to credit risk, interest rate risk, extension risk, and prepayment risk, among other risks. Mortgage-backed and asset-backed securities not issued by a government agency generally involve greater credit risk than securities issued by government agencies. Payment of principal and interest generally depends on the cash flows generated by the underlying assets and the terms of the security. The types of mortgages (for example, residential or commercial mortgages) underlying securities held by the Fund may differ and be affected differently by market factors. The Fund’s investments in mortgage-backed securities may make the Fund’s net asset value more susceptible to economic, market, political, and other developments affecting the residential and commercial real estate markets and

the servicing of mortgage loans secured by real estate properties. During periods of difficult economic conditions, delinquencies and losses on commercial mortgage-backed investments in particular generally increase, including as a result of the effects of those conditions on commercial real estate markets, the ability of commercial tenants to make loan payments, and the ability of a property to attract and retain commercial tenants. Investments that receive only the interest portion or the principal portion of payments on the underlying assets may be highly volatile. Litigation with respect to the representations and warranties given in connection with the issuance of mortgage-backed securities can be an important consideration in investing in such securities, and the outcome of any such litigation could significantly impact the value of the Fund’s mortgage-backed investments.

Preferred Stock Risk Like other equity securities, preferred stock is subject to the risk that its value may decrease based on actual or perceived changes in the business or financial condition of the issuer. In addition, changes in interest rates may adversely affect the value of a preferred stock that pays a fixed dividend. Preferred stocks are also subject to additional risks, such as potentially greater volatility and risks related to deferral, non-cumulative dividends, subordination, liquidity, limited voting rights, and special redemption rights.

Real Estate Risk; REIT Risk Real estate-related investments may decline in value as a result of factors affecting the real estate industry, such as the supply of real property in certain markets, changes in zoning laws, environmental regulations and other governmental action, delays in completion of construction, changes in real estate values, changes in property taxes, levels of occupancy, losses due to natural disasters, and local and regional market conditions. Investments in REITs may be subject to risks similar to those associated with direct investment in real estate, as well as additional risks associated with equity investments. As a shareholder in a REIT, the Fund, and indirectly the Fund’s shareholders, would bear its ratable share of the REIT’s expenses and would at the same time continue to pay its own fees and expenses.

Repurchase Agreement Risk  These transactions must be fully collateralized, but involve credit risk to a Fund if the other party should default on its obligation and the Fund is delayed or prevented from recovering the collateral.

Restricted Securities Risk The Fund may hold securities that are restricted as to resale under the U.S. federal securities laws, such as securities in certain privately held companies. Such securities may be highly illiquid and their values may experience significant volatility. Restricted securities may be difficult to value.

Sector Risk The Fund may allocate more of its assets to particular industries or to particular economic, market, or industry sectors than to others. This could increase the volatility of the Fund’s portfolio, and the Fund’s performance may be more susceptible to developments affecting issuers in those industries or sectors than if the Fund invested more broadly.

Small and Mid-Cap Company Risk Market risk and liquidity risk are particularly pronounced for securities of small and medium-sized companies, which may trade less frequently and in smaller volumes than more widely-held securities, and may fluctuate in price more than other securities. Their shares can be less liquid than those of larger companies, especially during market declines. Small and medium-sized companies may have limited product lines, markets, or financial resources and may be dependent on a limited management group; they may have been recently organized and have little or no track record of success.

Sovereign Debt Obligations Risk Investments in debt securities issued by governments or by government agencies and instrumentalities involve the risk that the governmental entities responsible for repayment may be unable or unwilling to pay interest and repay principal when due. Many sovereign debt obligations may be rated below investment grade (“junk” or “high yield” bonds). Any restructuring of a sovereign debt obligation held by the Fund will likely have a significant adverse effect on the value of the obligation. In the event of default of sovereign debt, the Fund may be unable to pursue legal action against the sovereign issuer or to realize on collateral securing the debt.

U.S. Government Securities Risk Obligations of certain U.S. Government agencies and instrumentalities are not backed by the full faith and credit of the U.S. Government, and there can be no assurance that the U.S. Government would provide financial support to such agencies and instrumentalities.

Valuation Risk The Fund is subject to the risk of mispricing or improper valuation of its investments, in particular to the extent that its securities are fair valued.

Value Company Risk The value investment approach entails the risk that the market will not recognize a security’s intrinsic value for a long time, or that a stock the investment adviser or subadviser judges to be undervalued may actually be appropriately priced.

When-Issued, Delayed Delivery, TBA, and Forward Commitment Transaction Risk These transactions may create leverage and involve a risk of loss if the value of the securities declines prior to settlement.

Performance Information

The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows changes in the Fund’s performance from year to year for Class II shares. The table shows how the Fund’s average annual returns for 1 year, and since inception, compare with those of a broad measure of market performance and an additional index that MML Advisers believes is a better comparison for the Fund’s investment strategy (Lipper Balanced Fund Index). Performance shown does not reflect the fees and expenses deducted under the variable life insurance or variable annuity contract through which you invest in the Fund. If these amounts were reflected, returns would be less than those shown. Past performance is not necessarily an indication of how the Fund will perform in the future.

Annual Performance

Class II Shares

Average Annual Total Returns

(for the periods ended December 31, 2024)

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(1)

Effective July 24, 2024, the MSCI ACWI replaced the S&P 500 Index as a broad measure of market performance in accordance with new regulatory disclosure requirements.

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MANAGEMENT

Investment Adviser: MML Investment Advisers, LLC (“MML Advisers”)

Subadviser(s):  BlackRock Investment Management, LLC (“BlackRock”)

Portfolio Manager(s):

Michael J. Abata, CFA is a portfolio manager at MML Advisers. He has managed the Fund since May 2023.

Suzanne Ly, CFA is a Managing Director at BlackRock. She has managed the Fund since January 2025.

Peter Tsang is a Director at BlackRock. He has managed the Fund since January 2025.

PURCHASE AND SALE OF FUND SHARES

Shares of the Fund are generally available to separate investment accounts of variable life insurance and variable annuity contracts offered by companies such as MassMutual. An investor should consult the company issuing the investor’s variable life insurance or variable annuity contract to determine how to make redemptions.

TAX INFORMATION

Dividends and capital gain distributions are paid to the insurance company separate accounts. Variable life insurance and variable annuity contract owners should refer to the variable life insurance or variable annuity product prospectus or consult with their own tax adviser for information regarding the tax consequences of their investment.

PAYMENTS TO INSURANCE COMPANIES AND THEIR AFFILIATES

The Fund is not sold directly to the general public but instead is offered as an underlying investment option for variable insurance contracts. The Fund

and its related companies may make payments to the sponsoring insurance company (or its affiliates) or other intermediary for distribution and/or other services. These payments may be a factor that the insurance company considers in including the Fund as an underlying investment option in the variable insurance contract or may create a conflict

of interest by influencing the insurance company or other intermediary to recommend the variable insurance contract over another investment. The prospectus (or other offering document) for your variable insurance contract may contain additional information about these payments.

INVESTMENT OBJECTIVE

The Fund seeks to achieve as high a total return over time as is considered consistent with prudent investment risk, preservation of capital and recognition of the Fund’s stated asset allocation.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. The expenses in the table do not reflect deductions at the separate account level or contract level for any charges that may be incurred under a variable life insurance or variable annuity contract. If these charges were reflected, the fees and expenses in the table would be higher.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

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(1)

Because Total Annual Fund Operating Expenses include Acquired Fund Fees and Expenses, they may not correspond to the ratios of expenses to average daily net assets shown in the “Financial Highlights” tables in the Prospectus, which reflect the operating expenses of the Fund and do not include Acquired Fund Fees and Expenses.

​

(2)

The expenses in the above table reflect a written agreement by MML Advisers to cap the fees and expenses of the Fund (other than extraordinary legal and other expenses, interest expense, expenses related to borrowings, securities lending, leverage, taxes, and brokerage, short sale dividend and loan expense, or other non-recurring or unusual expenses such as organizational expenses and shareholder meeting expenses, as applicable) through April 30, 2026, to the extent that Total Annual Fund Operating Expenses after Expense Reimbursement would otherwise exceed 0.50% and 0.75% for Class II and Service Class I shares, respectively. The Total Annual Fund Operating Expenses after Expense Reimbursement shown in the above table may exceed these amounts, because, as noted in the previous sentence, certain fees and expenses are excluded from the cap. The agreement can only be terminated by mutual consent of the Board of Trustees on behalf of the Fund and MML Advisers.

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Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that

you invest $10,000 in each share class of the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment earns a 5% return each year and that the Fund’s operating expenses are exactly as described in the preceding table. If separate account or variable life insurance or variable annuity contract expenses were included, overall expenses would be higher. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 6% of the average value of its portfolio.

INVESTMENTS, RISKS, AND PERFORMANCE​

Principal Investment Strategies

The Fund is a “fund of funds” that seeks to achieve its investment objective by allocating substantially all of its assets among exchange-traded funds (“ETFs”) providing exposures to various asset classes. The Fund’s investment adviser, MML Investment Advisers, LLC (“MML Advisers”), determines the Fund’s asset allocation strategy and implements this strategy by selecting ETFs for investment and determining the amounts of the Fund’s assets to be invested in each. The ETFs MML Advisers will consider for investment by the Fund will provide exposures to equity securities or to fixed-income securities. BlackRock Investment Management, LLC (“BlackRock”) is the Fund’s subadviser, and is responsible solely for the trading and execution of MML Advisers’ investment and allocation decisions. Under normal circumstances, the Fund invests at least 80% (and, typically, substantially all) of its net assets (plus the amount of any borrowings for investment purposes) in

iShares® ETFs*. iShares ETFs are advised by an affiliate of BlackRock.

The Fund typically invests approximately 80% of its net assets in equity ETFs and approximately 20% of its net assets in fixed income ETFs. Equity ETFs may include funds that provide exposures to, among other things, domestic and international equity securities, including common stocks, preferred stocks, securities convertible into common or preferred stock, rights, and warrants, of issuers of any size, as well as real estate investment trusts (“REITs”). Fixed income ETFs may include funds that provide exposures to, among other things, domestic and non-U.S. bonds, U.S. Government securities, non-U.S. sovereign obligations, mortgage-backed securities, securities below investment grade (“junk” or “high yield” bonds, including securities in default), inflation-protected securities, bank loans, and cash or money market instruments.

The Fund’s equity allocation may include equity exposures chosen by reference to, for example, style (including both value and growth funds), market capitalization (including both large-cap and small-cap funds), global investments (including domestic and international (including emerging market) funds), or other factors. The Fund’s fixed-income allocation may include exposures chosen by reference to, for example, sector (including government, corporate, agency, mortgage-backed securities, and other sectors), duration (a calculation of the average life of a bond which measures its price risk), credit quality (including securities below investment grade (“junk” or “high yield” bonds, including securities in default)), geographic location, or other factors. The percentage allocation to the various types of equity and fixed-income securities are determined at the discretion of MML Advisers.

MML Advisers will typically rebalance to these strategic targets on a quarterly basis. MML Advisers may at any time reassess and make revisions in the Fund’s asset allocation strategy consistent with the Fund’s investment objective and strategy, including revising the weightings among the investments described above and adding or removing ETFs from the asset allocation strategy. Actual allocations between equity and fixed income investments will typically not vary from the Fund’s target asset allocations by more than 10%, although MML Advisers may determine in light

*

iShares® and BlackRock® are registered trademarks of BlackRock, Inc. and its affiliates and are used under license.

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of market conditions or other factors that a greater variation is warranted to protect the Fund or achieve its investment goal. BlackRock will place, and oversee the execution of, trades as directed by MML Advisers to implement the asset allocation strategy.

ETFs in which the Fund invests may use derivatives contracts to achieve their investment objectives. Use of derivatives by an ETF may create investment leverage.

An ETF may enter into dollar roll or reverse repurchase agreement transactions. Some investments by an ETF may be restricted as to resale or otherwise considered to be illiquid. The Fund or an ETF may enter into repurchase agreement transactions. The Fund will bear a pro rata share of the ETFs’ expenses. The Fund also bears all of the risks associated with the investment strategies used by the ETFs.

Through its investments in ETFs, the Fund may at times have significant exposure to one or more industries or sectors. The Fund may hold a portion of its assets in cash or cash equivalents. A description of the ETFs in which the Fund expects to invest is included in Appendix D of the Statement of Additional Information (“SAI”).

Because the Fund will invest substantially all of its assets in ETFs advised by an affiliate of BlackRock, the Fund will not invest in ETFs advised or sponsored by others, even if they are less expensive or have better historical performance records. BlackRock does not receive a subadvisory fee for its services; it does, however, receive fees from the ETFs in which the Fund invests. MML Advisers might be seen to be subject to a conflict of interest, having an interest in selecting ETFs to provide an appropriate level of revenue or other benefits to BlackRock. MML Advisers has advised the Fund that, as a fiduciary to the Fund, MML Advisers has a duty to put the best interests of the Fund ahead of its own interest and that, consequently, it will make investment decisions for the Fund in the best interest of the Fund to achieve the Fund’s investment objectives and not for the benefit of MML Advisers, without regard to any benefit to BlackRock from the selection of different ETFs.

Principal Risks

The following are the Principal Risks of the Fund. The value of your investment in the Fund could go down as well as up. You can lose money by investing in the Fund. Although the descriptions

below refer to the risks relating to investment activities of the Fund, many of the risks arise due to the investment activities of the ETFs in which it invests. Certain risks relating to instruments and strategies used in the management of the Fund are placed first. The significance of any specific risk to an investment in the Fund will vary over time, depending on the composition of the Fund’s portfolio, market conditions, and other factors. You should read all of the risk information presented below carefully, because any one or more of these risks may result in losses to the Fund.

Allocation Risk There is no assurance that allocation decisions will result in the desired performance effects. There is a risk that MML Advisers’ evaluations and assumptions regarding asset classes or ETFs may be incorrect in view of actual market conditions. The requirement that substantially all of the Fund’s assets be invested in ETFs advised by an affiliate of BlackRock as noted in “Principal Investment Strategies” may adversely affect Fund performance.

Risk of Investment in Other Funds or Pools The Fund is indirectly exposed to all of the risks of the underlying funds, including ETFs, in which it invests, including the risk that the underlying funds will not perform as expected. ETFs are subject to additional risks, including secondary market trading risks and the risk that an ETF’s shares may trade above or below net asset value. The Fund indirectly pays a portion of the expenses incurred by the underlying funds, which may, in the case of an ETF, include a portion of the expenses incurred below their net asset value.

Bank Loans Risk Many of the risks associated with bank loans are similar to the risks of investing in below investment grade debt securities. Changes in the financial condition of the borrower or economic conditions or other circumstances may reduce the capacity of the borrower to make principal and interest payments on such instruments and may lead to defaults. Senior secured bank loans are typically supported by collateral; however the value of the collateral may be insufficient to cover the amount owed to the Fund, or the Fund may be prevented or delayed from realizing on the collateral. Some loans may be unsecured; unsecured loans generally present a greater risk of loss to the Fund if the issuer defaults. If the Fund relies on a third party to administer a loan, the Fund is subject to the risk that the third party will fail to perform its obligations. In addition, if the Fund holds only a

participation interest in a loan made by a third party, the Fund’s receipt of payments on the loan will depend on the third party’s willingness and ability to make those payments to the Fund. The settlement time for certain loans is longer than the settlement time for many other types of investments, and the Fund may not receive the payment for a loan sold by it until well after the sale; that cash would be unavailable for payment of redemption proceeds or for reinvestment. Interests in some bank loans may not be readily marketable and may be subject to restrictions on resale. In some cases, negotiations involved in disposing of indebtedness may require weeks to complete. Consequently, some indebtedness may be difficult or impossible to dispose of readily at what the Fund believes to be a fair price. Some loans may not be considered “securities” for certain purposes under the federal securities laws, and purchasers, such as the Fund, therefore may not be entitled to rely on the anti-fraud protections of the federal securities laws.

Below Investment Grade Debt Securities Risk Below investment grade debt securities, commonly known as “junk” or “high yield” bonds, have speculative characteristics and involve greater volatility of price and yield, greater risk of loss of principal and interest, and generally reflect a greater possibility of an adverse change in financial condition that could affect an issuer’s ability to honor its obligations.

Cash Position Risk If the Fund holds a significant portion of its assets in cash or cash equivalents, its investment returns may be adversely affected and the Fund may not achieve its investment objective.

Convertible Securities Risk Convertible securities are subject to the risks of both debt instruments and equity securities. The price of a convertible security may change in response to changes in price of the underlying equity security, the credit quality of the issuer, and interest rates. In general, the values of convertible securities tend to decline as interest rates rise and to rise when interest rates fall. A convertible security generally has less potential for gain or loss than the underlying equity security.

Credit Risk Credit risk is the risk that an issuer, guarantor, or liquidity provider of a fixed income security held by the Fund may be unable or unwilling, or may be perceived (whether by market participants, ratings agencies, pricing services or otherwise) as unable or unwilling, to make timely principal and/or interest payments, or to otherwise

honor its obligations. The Fund may also be exposed to the credit risk of its counterparty to repurchase agreements, reverse repurchase agreements, swap transactions, and other derivatives transactions, and to the counterparty’s ability or willingness to perform in accordance with the terms of the transaction. The value of such transactions to the Fund will depend on the willingness and ability of the counterparty to perform its obligations, including among other things the obligation to return collateral or margin to the Fund. If a counterparty becomes bankrupt or otherwise fails to perform its obligations under a derivative contract due to financial difficulties, the Fund may experience significant delays in obtaining any recovery under the derivative contract in a bankruptcy or other reorganization proceeding. The Fund may obtain only a limited recovery or may obtain no recovery in such circumstances.

Defaulted and Distressed Securities Risk Because the issuer of such securities is in default and is likely to be in distressed financial condition, repayment of defaulted securities and obligations of distressed issuers (including insolvent issuers or issuers in payment or covenant default, in workout or restructuring, or in bankruptcy or insolvency proceedings) is uncertain. To the extent the Fund is invested in distressed securities, its ability to achieve current income for its shareholders may be diminished.

Derivatives Risk Derivatives can be highly volatile and involve risks different from, and potentially greater than, direct investments, including risks of imperfect correlation between the value of derivatives and underlying assets, counterparty default, potential losses that partially or completely offset gains, and illiquidity. Derivatives can create investment leverage. Losses from derivatives can be substantially greater than the derivatives’ original cost and can sometimes be unlimited. If the value of a derivative does not correlate well with the particular market or asset class the derivative is designed to provide exposure to, the derivative may not have the effect or benefit anticipated. Derivatives can also reduce the opportunity for gains or result in losses by offsetting positive returns in other investments. Many derivatives are traded in the over-the-counter market and not on exchanges.

Dollar Roll and Reverse Repurchase Agreement Transaction Risk These transactions generally create leverage and subject the Fund to the credit risk of the counterparty.

Equity Securities Risk Although stocks may have the potential to outperform other asset classes over the long term, their prices tend to fluctuate more dramatically over the shorter term. These movements may result from factors affecting individual companies, or from broader influences like changes in interest rates, market conditions, or investor confidence, or announcements of economic, political, or financial information.

Fixed Income Securities Risk The values of fixed income securities typically will decline during periods of rising interest rates, and can also decline in response to changes in the financial condition of the issuer, borrower, counterparty, or underlying collateral assets, or changes in market, economic, industry, political, regulatory, public health, and other conditions affecting a particular type of security or issuer or fixed income securities generally. Certain events, such as market or economic developments, regulatory or government actions, natural disasters, pandemics, terrorist attacks, war, and other geopolitical events can have a dramatic adverse effect on the debt market and the overall liquidity of the market for fixed income securities. During those periods, the Fund may experience high levels of shareholder redemptions, and may have to sell securities at times when the Fund would otherwise not do so, and potentially at unfavorable prices. Certain securities may be difficult to value during such periods. Fixed income securities are subject to interest rate risk (the risk that the value of a fixed income security will fall when interest rates rise), extension risk (the risk that the average life of a security will be extended through a slowing of principal payments), prepayment risk (the risk that a security will be prepaid and the Fund will be required to reinvest at a less favorable rate), duration risk (the risk that longer-term securities may be more sensitive to interest rate changes), inflation risk (the risk that as inflation increases, the present value of the Fund’s fixed income investment typically will decline), and credit risk.

Foreign Investment Risk; Emerging Markets Risk; Currency Risk Investments in securities of foreign issuers, securities of companies with significant foreign exposure, and foreign currencies can involve additional risks relating to market, industry, political, regulatory, public health, and other conditions. Political, social, diplomatic, and economic developments, U.S. and foreign government action, or threat thereof, such as the imposition of currency or capital blockages, controls, or tariffs, economic and trade sanctions

or embargoes, security trading suspensions, entering or exiting trade or other intergovernmental agreements, or the expropriation or nationalization of assets in a particular country, can cause dramatic declines in certain or all securities with exposure to that country and other countries. Sanctions, or the threat of sanctions, may cause volatility in regional and global markets and may negatively impact the performance of various sectors and industries, as well as companies in other countries, which could have a negative effect on the performance of the Fund. In the event of nationalization, expropriation, confiscation, or other government action, intervention, or restriction, the Fund could lose its entire investment in a particular foreign issuer or country. There may be quotas or other limits on the ability of the Fund (or clients of the Fund’s investment adviser or subadviser) to invest or maintain investments in securities of issuers in certain countries. Enforcing legal rights can be more difficult, costly, and limited in certain foreign countries and with respect to certain types of investments, and can be particularly difficult against foreign governments. Because non-U.S. securities are normally denominated and traded in currencies other than the U.S. dollar, the value of the Fund’s assets may be affected favorably or unfavorably by changes in currency exchange rates, exchange control regulations, and restrictions or prohibitions on the repatriation of non-U.S. currencies. Income and gains with respect to investments in certain countries may be subject to withholding and other taxes. There may be less information publicly available about a non-U.S. company than about a U.S. company, and many non-U.S. companies are not subject to accounting, auditing, and financial reporting standards, regulatory framework and practices comparable to those in the U.S. The securities of some non-U.S. companies, especially those in emerging markets, are less liquid and at times more volatile than securities of comparable U.S. companies. Emerging markets securities are subject to greater risks than securities issued in developed foreign markets, including less liquidity, less stringent investor protection and disclosure standards, less reliable settlement practices, greater price volatility, higher relative rates of inflation, greater political, economic, and social instability, greater custody and operational risks, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater volatility in currency exchange rates, and are more susceptible to environmental problems. Many

emerging market countries are highly reliant on international trade and exports, including the export of commodities. Their economies may be significantly impacted by fluctuations in commodity prices and the global demand for certain commodities. In addition, pandemics and outbreaks of contagious diseases may exacerbate pre-existing problems in emerging market countries with less established health care systems. Frontier markets, a subset of emerging markets, generally have smaller economies and less mature capital markets than emerging markets. As a result, the risks of investing in emerging market countries are magnified in frontier market countries. Frontier markets are more susceptible to having abrupt changes in currency values, less mature markets and settlement practices, and lower trading volumes that could lead to greater price volatility and illiquidity. Non-U.S. transaction costs, such as brokerage commissions and custody costs, may be higher than in the United States. In addition, foreign markets can react differently to market, economic, industry, political, regulatory, geopolitical, public health, and other conditions than the U.S. market. The Fund may invest in foreign securities known as depositary receipts. Investments in depositary receipts are subject to the same risks as direct investment in foreign securities, which include market, political, currency, and regulatory risks.

Geographic Focus Risk When the Fund focuses investments on a particular country, group of countries, or geographic region, its performance will be closely tied to the market, currency, economic, political, or regulatory conditions and developments in those countries or that region, and could be more volatile than the performance of more geographically diversified funds.

Growth Company Risk The prices of growth securities are often highly sensitive to market fluctuations because of their heavy dependence on future earnings or cash flow expectations, and can be more volatile than the market in general.

Hedging Risk The Fund’s attempts at hedging and taking long and short positions in currencies may not be successful and could cause the Fund to lose money or fail to get the benefit of a gain on a hedged position. If expected changes to securities prices, interest rates, currency values, and exchange rates, or the creditworthiness of an issuer are not accurately predicted, the Fund could be in a worse position than if it had not entered into such transactions.

Index Funds Risk Certain ETFs may attempt to track the performance of a specified index. Therefore, securities may be purchased, retained, and sold by the ETF at times when an actively managed fund would not do so. The structure and composition of the index will affect the performance, volatility, and risk of the index and, consequently, the performance, volatility, and risk of the ETF. While the investment adviser or subadviser seeks to track the performance of the index (i.e., achieve a high degree of correlation with the index), the ETF’s return may not match the return of the index. The ETF incurs a number of operating expenses not applicable to the index, and may incur costs in buying and selling securities. In addition, the ETF may not be fully invested at times, generally as a result of cash flows into or out of the ETF.

Inflation-Linked Securities Risk Such securities may change in value in response to actual or anticipated changes in inflation rates in a manner unanticipated by the Fund’s portfolio manager or investors generally. Inflation-linked securities are subject to fixed income securities risks. When inflation is low, declining, or negative, the Fund’s performance could lag the performance of more conventional bond funds. Inflation rates may change frequently and drastically as a result of various factors, including unexpected shifts in the domestic or global economy (or expectations that such policies will change), and the Fund’s investments may not keep pace with inflation, which may result in losses to the Fund’s investors.

Large Company Risk Large-capitalization stocks as a group could fall out of favor with the market, causing the Fund’s investments in large-capitalization stocks to underperform investments that focus on small- or medium-capitalization stocks. Larger, more established companies may be slow to respond to challenges and may grow more slowly than smaller companies.

Leveraging Risk Instruments and transactions, including derivatives, dollar roll, and reverse repurchase agreement transactions, that create leverage may cause the value of an investment in the Fund to be more volatile, could result in larger losses than if they were not used, and tend to compound the effects of other risks.

Liquidity Risk Certain securities may be difficult (or impossible) to sell or certain positions may be difficult to close out at a desirable time and price, and the Fund may be required to hold an illiquid investment that is declining in value, or it may

be required to sell certain illiquid investments at a price or time that is not advantageous in order to meet redemptions or other cash needs. Some securities may be subject to restrictions on resale. There can be no assurance that there will be a liquid market for instruments held by the Fund at any time. The Fund may not receive the proceeds from the sale of certain investments for an extended period.

Management and Operational Risk The Fund relies on the manager’s investment analysis and its selection of investments to achieve its investment objective, and the Fund is subject to the risk that the manager’s assessment of an investment is wrong. There can be no assurance that the Fund will achieve the intended results and the Fund may incur significant losses. The Fund also runs the risk that deficiencies in the investment adviser’s, subadviser’s, or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

Market Risk The value of the Fund’s portfolio securities may decline, at times sharply and unpredictably, as a result of unfavorable market-induced changes affecting particular industries, sectors, or issuers. Stock and bond markets can decline significantly in response to issuer, market, economic, industry, political, regulatory, geopolitical, public health, and other conditions, as well as investor perceptions of these conditions. The Fund is subject to risks affecting issuers, such as management performance, financial leverage, industry problems, and reduced demand for goods or services.

Mortgage- and Asset-Backed Securities Risk Investments in mortgage- and asset-backed securities subject the Fund to credit risk, interest rate risk, extension risk, and prepayment risk, among other risks. Mortgage-backed and asset-backed securities not issued by a government agency generally involve greater credit risk than securities issued by government agencies. Payment of principal and interest generally depends on the cash flows generated by the underlying assets and the terms of the security. The types of mortgages (for example, residential or commercial mortgages) underlying securities held by the Fund may differ and be affected differently by market factors. The Fund’s investments in mortgage-backed securities may make the Fund’s net asset value more susceptible to economic, market, political, and other developments affecting the residential and commercial real estate markets and

the servicing of mortgage loans secured by real estate properties. During periods of difficult economic conditions, delinquencies and losses on commercial mortgage-backed investments in particular generally increase, including as a result of the effects of those conditions on commercial real estate markets, the ability of commercial tenants to make loan payments, and the ability of a property to attract and retain commercial tenants. Investments that receive only the interest portion or the principal portion of payments on the underlying assets may be highly volatile. Litigation with respect to the representations and warranties given in connection with the issuance of mortgage-backed securities can be an important consideration in investing in such securities, and the outcome of any such litigation could significantly impact the value of the Fund’s mortgage-backed investments.

Preferred Stock Risk Like other equity securities, preferred stock is subject to the risk that its value may decrease based on actual or perceived changes in the business or financial condition of the issuer. In addition, changes in interest rates may adversely affect the value of a preferred stock that pays a fixed dividend. Preferred stocks are also subject to additional risks, such as potentially greater volatility and risks related to deferral, non-cumulative dividends, subordination, liquidity, limited voting rights, and special redemption rights.

Real Estate Risk; REIT Risk Real estate-related investments may decline in value as a result of factors affecting the real estate industry, such as the supply of real property in certain markets, changes in zoning laws, environmental regulations and other governmental action, delays in completion of construction, changes in real estate values, changes in property taxes, levels of occupancy, losses due to natural disasters, and local and regional market conditions. Investments in REITs may be subject to risks similar to those associated with direct investment in real estate, as well as additional risks associated with equity investments. As a shareholder in a REIT, the Fund, and indirectly the Fund’s shareholders, would bear its ratable share of the REIT’s expenses and would at the same time continue to pay its own fees and expenses.

Repurchase Agreement Risk  These transactions must be fully collateralized, but involve credit risk to a Fund if the other party should default on its obligation and the Fund is delayed or prevented from recovering the collateral.

Restricted Securities Risk The Fund may hold securities that are restricted as to resale under the U.S. federal securities laws, such as securities in certain privately held companies. Such securities may be highly illiquid and their values may experience significant volatility. Restricted securities may be difficult to value.

Sector Risk The Fund may allocate more of its assets to particular industries or to particular economic, market, or industry sectors than to others. This could increase the volatility of the Fund’s portfolio, and the Fund’s performance may be more susceptible to developments affecting issuers in those industries or sectors than if the Fund invested more broadly.

Small and Mid-Cap Company Risk Market risk and liquidity risk are particularly pronounced for securities of small and medium-sized companies, which may trade less frequently and in smaller volumes than more widely-held securities, and may fluctuate in price more than other securities. Their shares can be less liquid than those of larger companies, especially during market declines. Small and medium-sized companies may have limited product lines, markets, or financial resources and may be dependent on a limited management group; they may have been recently organized and have little or no track record of success.

Sovereign Debt Obligations Risk Investments in debt securities issued by governments or by government agencies and instrumentalities involve the risk that the governmental entities responsible for repayment may be unable or unwilling to pay interest and repay principal when due. Many sovereign debt obligations may be rated below investment grade (“junk” or “high yield” bonds). Any restructuring of a sovereign debt obligation held by the Fund will likely have a significant adverse effect on the value of the obligation. In the event of default of sovereign debt, the Fund may be unable to pursue legal action against the sovereign issuer or to realize on collateral securing the debt.

U.S. Government Securities Risk Obligations of certain U.S. Government agencies and instrumentalities are not backed by the full faith and credit of the U.S. Government, and there can be no assurance that the U.S. Government would provide financial support to such agencies and instrumentalities.

Valuation Risk The Fund is subject to the risk of mispricing or improper valuation of its investments, in particular to the extent that its securities are fair valued.

Value Company Risk The value investment approach entails the risk that the market will not recognize a security’s intrinsic value for a long time, or that a stock the investment adviser or subadviser judges to be undervalued may actually be appropriately priced.

When-Issued, Delayed Delivery, TBA, and Forward Commitment Transaction Risk These transactions may create leverage and involve a risk of loss if the value of the securities declines prior to settlement.

Performance Information

The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows changes in the Fund’s performance from year to year for Class II shares. The table shows how the Fund’s average annual returns for 1 year, and since inception, compare with those of a broad measure of market performance and an additional index that MML Advisers believes is a better comparison for the Fund’s investment strategy (Lipper Balanced Fund Index). Performance shown does not reflect the fees and expenses deducted under the variable life insurance or variable annuity contract through which you invest in the Fund. If these amounts were reflected, returns would be less than those shown. Past performance is not necessarily an indication of how the Fund will perform in the future.

Annual Performance

Class II Shares

Average Annual Total Returns

(for the periods ended December 31, 2024)

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(1)

Effective July 24, 2024, the MSCI ACWI replaced the S&P 500 Index as a broad measure of market performance in accordance with new regulatory disclosure requirements.

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MANAGEMENT

Investment Adviser: MML Investment Advisers, LLC (“MML Advisers”)

Subadviser(s):  BlackRock Investment Management, LLC (“BlackRock”)

Portfolio Manager(s):

Michael J. Abata, CFA is a portfolio manager at MML Advisers. He has managed the Fund since May 2023.

Suzanne Ly, CFA is a Managing Director at BlackRock. She has managed the Fund since January 2025.

Peter Tsang is a Director at BlackRock. He has managed the Fund since January 2025.

PURCHASE AND SALE OF FUND SHARES

Shares of the Fund are generally available to separate investment accounts of variable life insurance and variable annuity contracts offered by companies such as MassMutual. An investor should consult the company issuing the investor’s variable life insurance or variable annuity contract to determine how to make redemptions.

TAX INFORMATION

Dividends and capital gain distributions are paid to the insurance company separate accounts. Variable life insurance and variable annuity contract owners should refer to the variable life insurance or variable annuity product prospectus or consult with their own tax adviser for information regarding the tax consequences of their investment.

PAYMENTS TO INSURANCE COMPANIES AND THEIR AFFILIATES

The Fund is not sold directly to the general public but instead is offered as an underlying investment option for variable insurance contracts. The Fund

and its related companies may make payments to the sponsoring insurance company (or its affiliates) or other intermediary for distribution and/or other services. These payments may be a factor that the insurance company considers in including the Fund as an underlying investment option in the variable insurance contract or may create a conflict

of interest by influencing the insurance company or other intermediary to recommend the variable insurance contract over another investment. The prospectus (or other offering document) for your variable insurance contract may contain additional information about these payments.

INVESTMENT OBJECTIVE

This Fund’s investment objective is to achieve as high a total rate of return on an annual basis as is considered consistent with the preservation of capital.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. The expenses in the table do not reflect deductions at the separate account level or contract level for any charges that may be incurred under a variable life insurance or variable annuity contract. If these charges were reflected, the fees and expenses in the table would be higher.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in each share class of the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment earns a 5% return each year and that the Fund’s operating expenses are exactly as described in the preceding table. If separate account or variable life insurance or variable annuity contract expenses were included, overall expenses would be higher. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the example, affect the

Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 222% of the average value of its portfolio.

INVESTMENTS, RISKS, AND PERFORMANCE​

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in investment grade fixed income securities (rated Baa3 or higher by Moody’s, BBB− or higher by Standard & Poor’s or the equivalent by any other nationally recognized statistical rating organization, or, if unrated, determined to be of comparable quality by the Fund’s subadviser, Barings LLC (“Barings”), or sub-subadviser, Baring International Investment Limited (“BIIL”)). These typically include U.S. dollar-denominated corporate obligations, securities issued or guaranteed by the U.S. Government or its agencies or instrumentalities, U.S. and foreign issuer dollar-denominated bonds including, but not limited to, corporate obligations, government and agency issues, private placement bonds, securities subject to resale pursuant to Rule 144A, and mortgage-backed and other asset-backed securities, including collateralized bond and loan obligations. In the event that a security is downgraded after its purchase by the Fund, the Fund may continue to hold the security if Barings or BIIL considers that doing so would be consistent with the Fund’s investment objective.

In pursuing its investment objective, the Fund may (but is not obligated to) use a wide variety of exchange-traded and over-the-counter derivatives, including, but not limited to, futures contracts and forward contracts, including derivatives thereof (for hedging purposes, to adjust various portfolio characteristics, including the duration (interest rate volatility) of the Fund’s portfolio, or as a substitute for direct investments); interest rate swaps (for hedging purposes or as a substitute for direct investments); total return swaps (for hedging purposes or to gain exposure to securities or markets in which it might not be able to invest directly); and credit default swaps (for hedging purposes or as a substitute for direct investments). The Fund may invest in common stocks, exchange-traded funds (“ETFs”), or other equity securities and derivatives thereof for hedging

purposes or to enhance total return. Use of derivatives by the Fund may create investment leverage.

The Fund may invest in money market securities, including commercial paper. The Fund may enter into repurchase agreement transactions. The Fund may at times have significant exposure to one or more industries or sectors. The Fund may hold a portion of its assets in cash or cash equivalents. The Fund may purchase and sell securities on a when-issued, delayed delivery, to-be-announced, or forward commitment basis, and may enter into dollar roll or reverse repurchase agreement transactions.

The Fund may invest in other investment companies, including investment companies that are advised by the Fund’s investment adviser, subadviser, sub-subadviser, or its affiliates, or by unaffiliated parties.

Barings or BIIL intends for the Fund’s portfolio dollar-weighted average duration generally to match (within 10%) the average duration of the Bloomberg U.S. Aggregate Bond Index (as of February 28, 2025, the average duration of the Index was 6.02 years). Duration measures the price sensitivity of a bond to changes in interest rates. Duration is the dollar weighted average time to maturity of a bond utilizing the present value of all future cash flows.

Barings or BIIL selects the Fund’s investments based on its analysis of opportunities and risks of various fixed income securities and market sectors. Currently, Barings or BIIL may consider the following factors (which may change over time and in particular cases): the perceived potential for high income offered by different types of corporate and government obligations (including mortgage-backed and other asset-backed securities); diversification among industries and issuers, credit ratings, and sectors; and the relative values offered by different securities. Barings or BIIL may choose to sell securities with deteriorating credit or limited upside potential compared to other securities.

The Fund expects that it will engage in active and frequent trading and so will typically have a relatively high portfolio turnover rate.

Principal Risks

The following are the Principal Risks of the Fund. The value of your investment in the Fund could go down as well as up. You can lose money by investing in the Fund. References in this section to the Fund’s subadviser may include any sub-subadvisers as applicable. Certain risks relating to instruments and strategies used in the management of the Fund are placed first. The significance of any specific risk to an investment in the Fund will vary over time, depending on the composition of the Fund’s portfolio, market conditions, and other factors. You should read all of the risk information presented below carefully, because any one or more of these risks may result in losses to the Fund.

Fixed Income Securities Risk The values of fixed income securities typically will decline during periods of rising interest rates, and can also decline in response to changes in the financial condition of the issuer, borrower, counterparty, or underlying collateral assets, or changes in market, economic, industry, political, regulatory, public health, and other conditions affecting a particular type of security or issuer or fixed income securities generally. Certain events, such as market or economic developments, regulatory or government actions, natural disasters, pandemics, terrorist attacks, war, and other geopolitical events can have a dramatic adverse effect on the debt market and the overall liquidity of the market for fixed income securities. During those periods, the Fund may experience high levels of shareholder redemptions, and may have to sell securities at times when the Fund would otherwise not do so, and potentially at unfavorable prices. Certain securities may be difficult to value during such periods. Fixed income securities are subject to interest rate risk (the risk that the value of a fixed income security will fall when interest rates rise), extension risk (the risk that the average life of a security will be extended through a slowing of principal payments), prepayment risk (the risk that a security will be prepaid and the Fund will be required to reinvest at a less favorable rate), duration risk (the risk that longer-term securities may be more sensitive to interest rate changes), inflation risk (the risk that as inflation increases, the present value of the Fund’s fixed income investment typically will decline), and credit risk.

Mortgage- and Asset-Backed Securities Risk Investments in mortgage- and asset-backed securities subject the Fund to credit risk, interest

rate risk, extension risk, and prepayment risk, among other risks. Mortgage-backed and asset-backed securities not issued by a government agency generally involve greater credit risk than securities issued by government agencies. Payment of principal and interest generally depends on the cash flows generated by the underlying assets and the terms of the security. The types of mortgages (for example, residential or commercial mortgages) underlying securities held by the Fund may differ and be affected differently by market factors. The Fund’s investments in mortgage-backed securities may make the Fund’s net asset value more susceptible to economic, market, political, and other developments affecting the residential and commercial real estate markets and the servicing of mortgage loans secured by real estate properties. During periods of difficult economic conditions, delinquencies and losses on commercial mortgage-backed investments in particular generally increase, including as a result of the effects of those conditions on commercial real estate markets, the ability of commercial tenants to make loan payments, and the ability of a property to attract and retain commercial tenants. Investments that receive only the interest portion or the principal portion of payments on the underlying assets may be highly volatile. Litigation with respect to the representations and warranties given in connection with the issuance of mortgage-backed securities can be an important consideration in investing in such securities, and the outcome of any such litigation could significantly impact the value of the Fund’s mortgage-backed investments.

Bank Loans Risk Many of the risks associated with bank loans are similar to the risks of investing in below investment grade debt securities. Changes in the financial condition of the borrower or economic conditions or other circumstances may reduce the capacity of the borrower to make principal and interest payments on such instruments and may lead to defaults. Senior secured bank loans are typically supported by collateral; however the value of the collateral may be insufficient to cover the amount owed to the Fund, or the Fund may be prevented or delayed from realizing on the collateral. Some loans may be unsecured; unsecured loans generally present a greater risk of loss to the Fund if the issuer defaults. If the Fund relies on a third party to administer a loan, the Fund is subject to the risk that the third party will fail to perform its obligations. In addition, if the Fund holds only a participation interest in a loan made by a third

party, the Fund’s receipt of payments on the loan will depend on the third party’s willingness and ability to make those payments to the Fund. The settlement time for certain loans is longer than the settlement time for many other types of investments, and the Fund may not receive the payment for a loan sold by it until well after the sale; that cash would be unavailable for payment of redemption proceeds or for reinvestment. Interests in some bank loans may not be readily marketable and may be subject to restrictions on resale. In some cases, negotiations involved in disposing of indebtedness may require weeks to complete. Consequently, some indebtedness may be difficult or impossible to dispose of readily at what the Fund believes to be a fair price. Some loans may not be considered “securities” for certain purposes under the federal securities laws, and purchasers, such as the Fund, therefore may not be entitled to rely on the anti-fraud protections of the federal securities laws.

Credit Risk Credit risk is the risk that an issuer, guarantor, or liquidity provider of a fixed income security held by the Fund may be unable or unwilling, or may be perceived (whether by market participants, ratings agencies, pricing services or otherwise) as unable or unwilling, to make timely principal and/or interest payments, or to otherwise honor its obligations. The Fund may also be exposed to the credit risk of its counterparty to repurchase agreements, reverse repurchase agreements, swap transactions, and other derivatives transactions, and to the counterparty’s ability or willingness to perform in accordance with the terms of the transaction. The value of such transactions to the Fund will depend on the willingness and ability of the counterparty to perform its obligations, including among other things the obligation to return collateral or margin to the Fund. If a counterparty becomes bankrupt or otherwise fails to perform its obligations under a derivative contract due to financial difficulties, the Fund may experience significant delays in obtaining any recovery under the derivative contract in a bankruptcy or other reorganization proceeding. The Fund may obtain only a limited recovery or may obtain no recovery in such circumstances.

Derivatives Risk Derivatives can be highly volatile and involve risks different from, and potentially greater than, direct investments, including risks of imperfect correlation between the value of derivatives and underlying assets, counterparty default, potential losses that partially or completely

offset gains, and illiquidity. Derivatives can create investment leverage. Losses from derivatives can be substantially greater than the derivatives’ original cost and can sometimes be unlimited. If the value of a derivative does not correlate well with the particular market or asset class the derivative is designed to provide exposure to, the derivative may not have the effect or benefit anticipated. Derivatives can also reduce the opportunity for gains or result in losses by offsetting positive returns in other investments. Many derivatives are traded in the over-the-counter market and not on exchanges.

Foreign Investment Risk; Emerging Markets Risk; Currency Risk Investments in securities of foreign issuers, securities of companies with significant foreign exposure, and foreign currencies can involve additional risks relating to market, industry, political, regulatory, public health, and other conditions. Political, social, diplomatic, and economic developments, U.S. and foreign government action, or threat thereof, such as the imposition of currency or capital blockages, controls, or tariffs, economic and trade sanctions or embargoes, security trading suspensions, entering or exiting trade or other intergovernmental agreements, or the expropriation or nationalization of assets in a particular country, can cause dramatic declines in certain or all securities with exposure to that country and other countries. Sanctions, or the threat of sanctions, may cause volatility in regional and global markets and may negatively impact the performance of various sectors and industries, as well as companies in other countries, which could have a negative effect on the performance of the Fund. In the event of nationalization, expropriation, confiscation, or other government action, intervention, or restriction, the Fund could lose its entire investment in a particular foreign issuer or country. There may be quotas or other limits on the ability of the Fund (or clients of the Fund’s investment adviser or subadviser) to invest or maintain investments in securities of issuers in certain countries. Enforcing legal rights can be more difficult, costly, and limited in certain foreign countries and with respect to certain types of investments, and can be particularly difficult against foreign governments. Because non-U.S. securities are normally denominated and traded in currencies other than the U.S. dollar, the value of the Fund’s assets may be affected favorably or unfavorably by changes in currency exchange rates, exchange control regulations, and restrictions or prohibitions on the repatriation of non-U.S.

currencies. Income and gains with respect to investments in certain countries may be subject to withholding and other taxes. There may be less information publicly available about a non-U.S. company than about a U.S. company, and many non-U.S. companies are not subject to accounting, auditing, and financial reporting standards, regulatory framework and practices comparable to those in the U.S. The securities of some non-U.S. companies, especially those in emerging markets, are less liquid and at times more volatile than securities of comparable U.S. companies. Emerging markets securities are subject to greater risks than securities issued in developed foreign markets, including less liquidity, less stringent investor protection and disclosure standards, less reliable settlement practices, greater price volatility, higher relative rates of inflation, greater political, economic, and social instability, greater custody and operational risks, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater volatility in currency exchange rates, and are more susceptible to environmental problems. Many emerging market countries are highly reliant on international trade and exports, including the export of commodities. Their economies may be significantly impacted by fluctuations in commodity prices and the global demand for certain commodities. In addition, pandemics and outbreaks of contagious diseases may exacerbate pre-existing problems in emerging market countries with less established health care systems. Frontier markets, a subset of emerging markets, generally have smaller economies and less mature capital markets than emerging markets. As a result, the risks of investing in emerging market countries are magnified in frontier market countries. Frontier markets are more susceptible to having abrupt changes in currency values, less mature markets and settlement practices, and lower trading volumes that could lead to greater price volatility and illiquidity. Non-U.S. transaction costs, such as brokerage commissions and custody costs, may be higher than in the United States. In addition, foreign markets can react differently to market, economic, industry, political, regulatory, geopolitical, public health, and other conditions than the U.S. market. The Fund may invest in foreign securities known as depositary receipts. Investments in depositary receipts are subject to the same risks as direct investment in foreign securities, which include market, political, currency, and regulatory risks.

Cash Position Risk If the Fund holds a significant portion of its assets in cash or cash equivalents,

its investment returns may be adversely affected and the Fund may not achieve its investment objective.

Defaulted and Distressed Securities Risk Because the issuer of such securities is in default and is likely to be in distressed financial condition, repayment of defaulted securities and obligations of distressed issuers (including insolvent issuers or issuers in payment or covenant default, in workout or restructuring, or in bankruptcy or insolvency proceedings) is uncertain. To the extent the Fund is invested in distressed securities, its ability to achieve current income for its shareholders may be diminished.

Dollar Roll and Reverse Repurchase Agreement Transaction Risk These transactions generally create leverage and subject the Fund to the credit risk of the counterparty.

Frequent Trading/Portfolio Turnover Risk Portfolio turnover generally involves some expense to the Fund. The trading costs associated with portfolio turnover may adversely affect the Fund’s performance.

Hedging Risk The Fund’s attempts at hedging and taking long and short positions in currencies may not be successful and could cause the Fund to lose money or fail to get the benefit of a gain on a hedged position. If expected changes to securities prices, interest rates, currency values, and exchange rates, or the creditworthiness of an issuer are not accurately predicted, the Fund could be in a worse position than if it had not entered into such transactions.

Inflation Risk The value of assets or income from the Fund’s investments will be less in the future as inflation decreases the value of money. As inflation increases, the value of the Fund’s assets can decline as can the value of the Fund’s distributions. Inflation rates may change frequently and drastically as a result of various factors, including unexpected shifts in the domestic or global economy (or expectations that such policies will change), and the Fund’s investments may not keep pace with inflation, which may result in losses to the Fund’s investors.

Leveraging Risk Instruments and transactions, including derivatives, dollar roll, and reverse repurchase agreement transactions, that create leverage may cause the value of an investment in the Fund to be more volatile, could result in larger losses than if they were not used, and tend to compound the effects of other risks.

Liquidity Risk Certain securities may be difficult (or impossible) to sell or certain positions may be difficult to close out at a desirable time and price, and the Fund may be required to hold an illiquid investment that is declining in value, or it may be required to sell certain illiquid investments at a price or time that is not advantageous in order to meet redemptions or other cash needs. Some securities may be subject to restrictions on resale. There can be no assurance that there will be a liquid market for instruments held by the Fund at any time. The Fund may not receive the proceeds from the sale of certain investments for an extended period.

Management and Operational Risk The Fund relies on the manager’s investment analysis and its selection of investments to achieve its investment objective, and the Fund is subject to the risk that the manager’s assessment of an investment is wrong. There can be no assurance that the Fund will achieve the intended results and the Fund may incur significant losses. The Fund also runs the risk that deficiencies in the investment adviser’s, subadviser’s, or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

Market Risk The value of the Fund’s portfolio securities may decline, at times sharply and unpredictably, as a result of unfavorable market-induced changes affecting particular industries, sectors, or issuers. Stock and bond markets can decline significantly in response to issuer, market, economic, industry, political, regulatory, geopolitical, public health, and other conditions, as well as investor perceptions of these conditions. The Fund is subject to risks affecting issuers, such as management performance, financial leverage, industry problems, and reduced demand for goods or services.

Reinvestment Risk Income from the Fund’s portfolio will decline if and when the Fund invests the proceeds from matured, traded, or called debt obligations at market interest rates that are below the portfolio’s current earnings rate. A decline in income could affect the Fund’s overall return.

Repurchase Agreement Risk  These transactions must be fully collateralized, but involve credit risk to a Fund if the other party should default on its obligation and the Fund is delayed or prevented from recovering the collateral.

Restricted Securities Risk The Fund may hold securities that are restricted as to resale under the

U.S. federal securities laws, such as securities in certain privately held companies. Such securities may be highly illiquid and their values may experience significant volatility. Restricted securities may be difficult to value.

Risk of Investment in Other Funds or Pools The Fund is indirectly exposed to all of the risks of the underlying funds, including ETFs, in which it invests, including the risk that the underlying funds will not perform as expected. ETFs are subject to additional risks, including secondary market trading risks and the risk that an ETF’s shares may trade above or below net asset value. The Fund indirectly pays a portion of the expenses incurred by the underlying funds, which may, in the case of an ETF, include a portion of the expenses incurred below their net asset value.

Sector Risk The Fund may allocate more of its assets to particular industries or to particular economic, market, or industry sectors than to others. This could increase the volatility of the Fund’s portfolio, and the Fund’s performance may be more susceptible to developments affecting issuers in those industries or sectors than if the Fund invested more broadly.

U.S. Government Securities Risk Obligations of certain U.S. Government agencies and instrumentalities are not backed by the full faith and credit of the U.S. Government, and there can be no assurance that the U.S. Government would provide financial support to such agencies and instrumentalities.

Valuation Risk The Fund is subject to the risk of mispricing or improper valuation of its investments, in particular to the extent that its securities are fair valued.

When-Issued, Delayed Delivery, TBA, and Forward Commitment Transaction Risk These transactions may create leverage and involve a risk of loss if the value of the securities declines prior to settlement.

Performance Information

The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows changes in the Fund’s performance from year to year for Initial Class shares. The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare with those of a broad measure of market performance. Performance shown does not reflect the fees and expenses deducted under the variable life insurance

or variable annuity contract through which you invest in the Fund. If these amounts were reflected, returns would be less than those shown. Past performance is not necessarily an indication of how the Fund will perform in the future.

Annual Performance

Initial Class Shares

Average Annual Total Returns

(for the periods ended December 31, 2024)

MANAGEMENT

Investment Adviser: MML Investment Advisers, LLC (“MML Advisers”)

Subadviser(s): Barings LLC (“Barings”)

Sub-subadviser(s):  Baring International Investment Limited (“BIIL”)

Portfolio Manager(s):

Stephen Ehrenberg, CFA is a Managing Director, portfolio manager for Barings’ Investment Grade Fixed Income Group, and Head of Barings’ North America Investment Grade Credit. He has managed the Fund since May 2019.

Rishi Kapur, CFA is a Managing Director, member of Barings’ Private Placements & Asset Based Finance Group, and Head of Barings’ Securitized Trading. He has managed the Fund since February 2025.

Charles Sanford is a Managing Director and the Head of, and a portfolio manager for, Barings’ Investment Grade Credit Group. He

has managed the Fund since December 2020. He previously managed the Fund from June 2006 to November 2017.

PURCHASE AND SALE OF FUND SHARES

Shares of the Fund are generally available to separate investment accounts of variable life insurance and variable annuity contracts offered by companies such as MassMutual. An investor should consult the company issuing the investor’s variable life insurance or variable annuity contract to determine how to make redemptions.

TAX INFORMATION

Dividends and capital gain distributions are paid to the insurance company separate accounts. Variable life insurance and variable annuity contract owners should refer to the variable life insurance or variable annuity product prospectus or consult with their own tax adviser for information regarding the tax consequences of their investment.

PAYMENTS TO INSURANCE COMPANIES AND THEIR AFFILIATES

The Fund is not sold directly to the general public but instead is offered as an underlying investment option for variable insurance contracts. The Fund and its related companies may make payments to the sponsoring insurance company (or its affiliates) or other intermediary for distribution and/or other services. These payments may be a factor that the insurance company considers in including the Fund as an underlying investment option in the variable insurance contract or may create a conflict of interest by influencing the insurance company or other intermediary to recommend the variable insurance contract over another investment. The prospectus (or other offering document) for your variable insurance contract may contain additional information about these payments.

INVESTMENT OBJECTIVE

This Fund seeks to achieve a high total rate of return primarily from current income while minimizing fluctuations in capital values by investing primarily in a diversified portfolio of short-term investment grade fixed income securities.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. The expenses in the table do not reflect deductions at the separate account level or contract level for any charges that may be incurred under a variable life insurance or variable annuity contract. If these charges were reflected, the fees and expenses in the table would be higher.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in each share class of the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment earns a 5% return each year and that the Fund’s operating expenses are exactly as described in the preceding table. If separate account or variable life insurance or variable annuity contract expenses were included, overall expenses would be higher. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs.

These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 48% of the average value of its portfolio.

INVESTMENTS, RISKS, AND PERFORMANCE​

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in investment grade fixed income securities (rated Baa3 or higher by Moody’s, BBB- or higher by Standard & Poor’s or the equivalent by any other nationally recognized statistical rating organization, or, if unrated, determined to be of comparable quality by the Fund’s subadviser, Barings LLC (“Barings”), or sub-subadviser, Baring International InvestmentLimited (“BIIL”)). These typically include U.S. dollar-denominated corporate obligations, securities issued or guaranteed by the U.S. Government or its agencies or instrumentalities, U.S. and foreign issuer dollar-denominated bonds including, but not limited to, corporate obligations, government and agency issues, private placement bonds, securities subject to resale pursuant to Rule 144A, and mortgage-backed and other asset-backed securities, including collateralized bond and loan obligations.

The Fund may also invest in below investment grade debt securities (“junk” or “high yield” bonds), including securities in default, and including bank loans; normally, 10% or less of the Fund’s total assets will be invested in below investment grade debt securities. In the event that a security is downgraded after its purchase by the Fund, the Fund may continue to hold the security if Barings or BIIL considers that doing so would be consistent with the Fund’s investment objective.

The Fund may invest up to 15% of its total assets in securities that are not denominated in U.S. dollars including, but not limited to, corporate obligations, government and agency issues, private placement bonds, and mortgage-backed and other asset-backed securities, including collateralized bond and loan obligations. Although the Fund’s investment in non-U.S. dollar denominated assets may be on a currency hedged or unhedged basis, under normal market conditions, the Fund seeks to hedge substantially all of its exposure to non-U.S.

currencies. The Fund may also invest in non-dollar denominated high yield bonds, including bank loans, and may invest in securities subject to legal restrictions on resale, some of which may be subject to resale pursuant to Rule 144A.

In pursuing its investment objective, the Fund may (but is not obligated to) use a wide variety of exchange-traded and over-the-counter derivatives, including, but not limited to, futures contracts, foreign currency futures and forward contracts, including derivatives thereof (for hedging purposes, to adjust various portfolio characteristics, including the duration (interest rate volatility) of the Fund’s portfolio, or as a substitute for direct investments); interest rate swaps (for hedging purposes or as a substitute for direct investments or to gain market exposure); total return swaps (for hedging purposes or as a substitute for direct investments); and credit default swaps (for hedging purposes or as a substitute for direct investments). The Fund may invest in common stocks, exchange-traded funds (“ETFs”), or other equity securities and derivatives thereof for hedging purposes or to enhance total return. Use of derivatives by the Fund may create investment leverage.

The Fund may invest in money market securities, including commercial paper. The Fund may enter into repurchase agreement transactions. The Fund may at times have significant exposure to one or more industries or sectors. The Fund may hold a portion of its assets in cash or cash equivalents. The Fund may purchase and sell securities on a when-issued, delayed delivery, to-be-announced, or forward commitment basis, and may enter into dollar roll or reverse repurchase agreement transactions.

The Fund may invest in (i) securities denominated in currencies of emerging market countries, (ii) fixed income securities or debt instruments issued by emerging market entities or sovereign nations and/or (iii) debt instruments denominated in or based on the currencies, interest rates, or issues of emerging market countries. Emerging market countries are defined to include any country that did not become a member of the Organization for Economic Cooperation and Development (O.E.C.D.) prior to 1975 and Turkey.

The Fund may invest in other investment companies, including investment companies that are advised by the Fund’s investment adviser, subadviser, sub-subadviser, or its affiliates, or by unaffiliated parties.

Barings or BIIL intends for the Fund’s portfolio dollar-weighted average duration generally to match (within 10%) the average duration of the Bloomberg U.S. Aggregate 1-3 Year Bond Index (as of February 28, 2025, the average duration of the Index was 1.76 years). Duration measures the price sensitivity of a bond to changes in interest rates. Duration is the dollar weighted average time to maturity of a bond utilizing the present value of all future cash flows.

Barings or BIIL generally selects the Fund’s investments based on its analysis of opportunities and risks of various securities and market sectors. Barings or BIIL may choose to sell securities with deteriorating credit or limited upside potential compared to other available securities.

The Fund expects that it will engage in active and frequent trading and so will typically have a relatively high portfolio turnover rate.

Principal Risks

The following are the Principal Risks of the Fund. The value of your investment in the Fund could go down as well as up. You can lose money by investing in the Fund. References in this section to the Fund’s subadviser may include any sub-subadvisers as applicable. Certain risks relating to instruments and strategies used in the management of the Fund are placed first. The significance of any specific risk to an investment in the Fund will vary over time, depending on the composition of the Fund’s portfolio, market conditions, and other factors. You should read all of the risk information presented below carefully, because any one or more of these risks may result in losses to the Fund.

Fixed Income Securities Risk The values of fixed income securities typically will decline during periods of rising interest rates, and can also decline in response to changes in the financial condition of the issuer, borrower, counterparty, or underlying collateral assets, or changes in market, economic, industry, political, regulatory, public health, and other conditions affecting a particular type of security or issuer or fixed income securities generally. Certain events, such as market or economic developments, regulatory or government actions, natural disasters, pandemics, terrorist attacks, war, and other geopolitical events can have a dramatic adverse effect on the debt market and the overall liquidity of the market for fixed income securities. During those periods, the Fund may experience high levels of shareholder redemptions, and may have to sell securities at times when the

Fund would otherwise not do so, and potentially at unfavorable prices. Certain securities may be difficult to value during such periods. Fixed income securities are subject to interest rate risk (the risk that the value of a fixed income security will fall when interest rates rise), extension risk (the risk that the average life of a security will be extended through a slowing of principal payments), prepayment risk (the risk that a security will be prepaid and the Fund will be required to reinvest at a less favorable rate), duration risk (the risk that longer-term securities may be more sensitive to interest rate changes), inflation risk (the risk that as inflation increases, the present value of the Fund’s fixed income investment typically will decline), and credit risk.

Mortgage- and Asset-Backed Securities Risk Investments in mortgage- and asset-backed securities subject the Fund to credit risk, interest rate risk, extension risk, and prepayment risk, among other risks. Mortgage-backed and asset-backed securities not issued by a government agency generally involve greater credit risk than securities issued by government agencies. Payment of principal and interest generally depends on the cash flows generated by the underlying assets and the terms of the security. The types of mortgages (for example, residential or commercial mortgages) underlying securities held by the Fund may differ and be affected differently by market factors. The Fund’s investments in mortgage-backed securities may make the Fund’s net asset value more susceptible to economic, market, political, and other developments affecting the residential and commercial real estate markets and the servicing of mortgage loans secured by real estate properties. During periods of difficult economic conditions, delinquencies and losses on commercial mortgage-backed investments in particular generally increase, including as a result of the effects of those conditions on commercial real estate markets, the ability of commercial tenants to make loan payments, and the ability of a property to attract and retain commercial tenants. Investments that receive only the interest portion or the principal portion of payments on the underlying assets may be highly volatile. Litigation with respect to the representations and warranties given in connection with the issuance of mortgage-backed securities can be an important consideration in investing in such securities, and the outcome of any such litigation could significantly impact the value of the Fund’s mortgage-backed investments.

Bank Loans Risk Many of the risks associated with bank loans are similar to the risks of investing

in below investment grade debt securities. Changes in the financial condition of the borrower or economic conditions or other circumstances may reduce the capacity of the borrower to make principal and interest payments on such instruments and may lead to defaults. Senior secured bank loans are typically supported by collateral; however the value of the collateral may be insufficient to cover the amount owed to the Fund, or the Fund may be prevented or delayed from realizing on the collateral. Some loans may be unsecured; unsecured loans generally present a greater risk of loss to the Fund if the issuer defaults. If the Fund relies on a third party to administer a loan, the Fund is subject to the risk that the third party will fail to perform its obligations. In addition, if the Fund holds only a participation interest in a loan made by a third party, the Fund’s receipt of payments on the loan will depend on the third party’s willingness and ability to make those payments to the Fund. The settlement time for certain loans is longer than the settlement time for many other types of investments, and the Fund may not receive the payment for a loan sold by it until well after the sale; that cash would be unavailable for payment of redemption proceeds or for reinvestment. Interests in some bank loans may not be readily marketable and may be subject to restrictions on resale. In some cases, negotiations involved in disposing of indebtedness may require weeks to complete. Consequently, some indebtedness may be difficult or impossible to dispose of readily at what the Fund believes to be a fair price. Some loans may not be considered “securities” for certain purposes under the federal securities laws, and purchasers, such as the Fund, therefore may not be entitled to rely on the anti-fraud protections of the federal securities laws.

Below Investment Grade Debt Securities Risk Below investment grade debt securities, commonly known as “junk” or “high yield” bonds, have speculative characteristics and involve greater volatility of price and yield, greater risk of loss of principal and interest, and generally reflect a greater possibility of an adverse change in financial condition that could affect an issuer’s ability to honor its obligations.

Credit Risk Credit risk is the risk that an issuer, guarantor, or liquidity provider of a fixed income security held by the Fund may be unable or unwilling, or may be perceived (whether by market participants, ratings agencies, pricing services or otherwise) as unable or unwilling, to make timely

principal and/or interest payments, or to otherwise honor its obligations. The Fund may also be exposed to the credit risk of its counterparty to repurchase agreements, reverse repurchase agreements, swap transactions, and other derivatives transactions, and to the counterparty’s ability or willingness to perform in accordance with the terms of the transaction. The value of such transactions to the Fund will depend on the willingness and ability of the counterparty to perform its obligations, including among other things the obligation to return collateral or margin to the Fund. If a counterparty becomes bankrupt or otherwise fails to perform its obligations under a derivative contract due to financial difficulties, the Fund may experience significant delays in obtaining any recovery under the derivative contract in a bankruptcy or other reorganization proceeding. The Fund may obtain only a limited recovery or may obtain no recovery in such circumstances.

Derivatives Risk Derivatives can be highly volatile and involve risks different from, and potentially greater than, direct investments, including risks of imperfect correlation between the value of derivatives and underlying assets, counterparty default, potential losses that partially or completely offset gains, and illiquidity. Derivatives can create investment leverage. Losses from derivatives can be substantially greater than the derivatives’ original cost and can sometimes be unlimited. If the value of a derivative does not correlate well with the particular market or asset class the derivative is designed to provide exposure to, the derivative may not have the effect or benefit anticipated. Derivatives can also reduce the opportunity for gains or result in losses by offsetting positive returns in other investments. Many derivatives are traded in the over-the-counter market and not on exchanges.

Foreign Investment Risk; Emerging Markets Risk; Currency Risk Investments in securities of foreign issuers, securities of companies with significant foreign exposure, and foreign currencies can involve additional risks relating to market, industry, political, regulatory, public health, and other conditions. Political, social, diplomatic, and economic developments, U.S. and foreign government action, or threat thereof, such as the imposition of currency or capital blockages, controls, or tariffs, economic and trade sanctions or embargoes, security trading suspensions, entering or exiting trade or other intergovernmental agreements, or the expropriation or nationalization

of assets in a particular country, can cause dramatic declines in certain or all securities with exposure to that country and other countries. Sanctions, or the threat of sanctions, may cause volatility in regional and global markets and may negatively impact the performance of various sectors and industries, as well as companies in other countries, which could have a negative effect on the performance of the Fund. In the event of nationalization, expropriation, confiscation, or other government action, intervention, or restriction, the Fund could lose its entire investment in a particular foreign issuer or country. There may be quotas or other limits on the ability of the Fund (or clients of the Fund’s investment adviser or subadviser) to invest or maintain investments in securities of issuers in certain countries. Enforcing legal rights can be more difficult, costly, and limited in certain foreign countries and with respect to certain types of investments, and can be particularly difficult against foreign governments. Because non-U.S. securities are normally denominated and traded in currencies other than the U.S. dollar, the value of the Fund’s assets may be affected favorably or unfavorably by changes in currency exchange rates, exchange control regulations, and restrictions or prohibitions on the repatriation of non-U.S. currencies. Income and gains with respect to investments in certain countries may be subject to withholding and other taxes. There may be less information publicly available about a non-U.S. company than about a U.S. company, and many non-U.S. companies are not subject to accounting, auditing, and financial reporting standards, regulatory framework and practices comparable to those in the U.S. The securities of some non-U.S. companies, especially those in emerging markets, are less liquid and at times more volatile than securities of comparable U.S. companies. Emerging markets securities are subject to greater risks than securities issued in developed foreign markets, including less liquidity, less stringent investor protection and disclosure standards, less reliable settlement practices, greater price volatility, higher relative rates of inflation, greater political, economic, and social instability, greater custody and operational risks, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater volatility in currency exchange rates, and are more susceptible to environmental problems. Many emerging market countries are highly reliant on international trade and exports, including the export of commodities. Their economies may be

significantly impacted by fluctuations in commodity prices and the global demand for certain commodities. In addition, pandemics and outbreaks of contagious diseases may exacerbate pre-existing problems in emerging market countries with less established health care systems. Frontier markets, a subset of emerging markets, generally have smaller economies and less mature capital markets than emerging markets. As a result, the risks of investing in emerging market countries are magnified in frontier market countries. Frontier markets are more susceptible to having abrupt changes in currency values, less mature markets and settlement practices, and lower trading volumes that could lead to greater price volatility and illiquidity. Non-U.S. transaction costs, such as brokerage commissions and custody costs, may be higher than in the United States. In addition, foreign markets can react differently to market, economic, industry, political, regulatory, geopolitical, public health, and other conditions than the U.S. market. The Fund may invest in foreign securities known as depositary receipts. Investments in depositary receipts are subject to the same risks as direct investment in foreign securities, which include market, political, currency, and regulatory risks.

Cash Position Risk If the Fund holds a significant portion of its assets in cash or cash equivalents, its investment returns may be adversely affected and the Fund may not achieve its investment objective.

Defaulted and Distressed Securities Risk Because the issuer of such securities is in default and is likely to be in distressed financial condition, repayment of defaulted securities and obligations of distressed issuers (including insolvent issuers or issuers in payment or covenant default, in workout or restructuring, or in bankruptcy or insolvency proceedings) is uncertain. To the extent the Fund is invested in distressed securities, its ability to achieve current income for its shareholders may be diminished.

Dollar Roll and Reverse Repurchase Agreement Transaction Risk These transactions generally create leverage and subject the Fund to the credit risk of the counterparty.

Frequent Trading/Portfolio Turnover Risk Portfolio turnover generally involves some expense to the Fund. The trading costs associated with portfolio turnover may adversely affect the Fund’s performance.

Hedging Risk The Fund’s attempts at hedging and taking long and short positions in currencies may

not be successful and could cause the Fund to lose money or fail to get the benefit of a gain on a hedged position. If expected changes to securities prices, interest rates, currency values, and exchange rates, or the creditworthiness of an issuer are not accurately predicted, the Fund could be in a worse position than if it had not entered into such transactions.

Inflation Risk The value of assets or income from the Fund’s investments will be less in the future as inflation decreases the value of money. As inflation increases, the value of the Fund’s assets can decline as can the value of the Fund’s distributions. Inflation rates may change frequently and drastically as a result of various factors, including unexpected shifts in the domestic or global economy (or expectations that such policies will change), and the Fund’s investments may not keep pace with inflation, which may result in losses to the Fund’s investors.

Leveraging Risk Instruments and transactions, including derivatives, dollar roll, and reverse repurchase agreement transactions, that create leverage may cause the value of an investment in the Fund to be more volatile, could result in larger losses than if they were not used, and tend to compound the effects of other risks.

Liquidity Risk Certain securities may be difficult (or impossible) to sell or certain positions may be difficult to close out at a desirable time and price, and the Fund may be required to hold an illiquid investment that is declining in value, or it may be required to sell certain illiquid investments at a price or time that is not advantageous in order to meet redemptions or other cash needs. Some securities may be subject to restrictions on resale. There can be no assurance that there will be a liquid market for instruments held by the Fund at any time. The Fund may not receive the proceeds from the sale of certain investments for an extended period.

Management and Operational Risk The Fund relies on the manager’s investment analysis and its selection of investments to achieve its investment objective, and the Fund is subject to the risk that the manager’s assessment of an investment is wrong. There can be no assurance that the Fund will achieve the intended results and the Fund may incur significant losses. The Fund also runs the risk that deficiencies in the investment adviser’s, subadviser’s, or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

Market Risk The value of the Fund’s portfolio securities may decline, at times sharply and unpredictably, as a result of unfavorable market-induced changes affecting particular industries, sectors, or issuers. Stock and bond markets can decline significantly in response to issuer, market, economic, industry, political, regulatory, geopolitical, public health, and other conditions, as well as investor perceptions of these conditions. The Fund is subject to risks affecting issuers, such as management performance, financial leverage, industry problems, and reduced demand for goods or services.

Reinvestment Risk Income from the Fund’s portfolio will decline if and when the Fund invests the proceeds from matured, traded, or called debt obligations at market interest rates that are below the portfolio’s current earnings rate. A decline in income could affect the Fund’s overall return.

Repurchase Agreement Risk  These transactions must be fully collateralized, but involve credit risk to a Fund if the other party should default on its obligation and the Fund is delayed or prevented from recovering the collateral.

Restricted Securities Risk The Fund may hold securities that are restricted as to resale under the U.S. federal securities laws, such as securities in certain privately held companies. Such securities may be highly illiquid and their values may experience significant volatility. Restricted securities may be difficult to value.

Risk of Investment in Other Funds or Pools The Fund is indirectly exposed to all of the risks of the underlying funds, including ETFs, in which it invests, including the risk that the underlying funds will not perform as expected. ETFs are subject to additional risks, including secondary market trading risks and the risk that an ETF’s shares may trade above or below net asset value. The Fund indirectly pays a portion of the expenses incurred by the underlying funds, which may, in the case of an ETF, include a portion of the expenses incurred below their net asset value.

Sector Risk The Fund may allocate more of its assets to particular industries or to particular economic, market, or industry sectors than to others. This could increase the volatility of the Fund’s portfolio, and the Fund’s performance may be more susceptible to developments affecting issuers in those industries or sectors than if the Fund invested more broadly.

Sovereign Debt Obligations Risk Investments in debt securities issued by governments or by government agencies and instrumentalities involve the risk that the governmental entities responsible for repayment may be unable or unwilling to pay interest and repay principal when due. Many sovereign debt obligations may be rated below investment grade (“junk” or “high yield” bonds). Any restructuring of a sovereign debt obligation held by the Fund will likely have a significant adverse effect on the value of the obligation. In the event of default of sovereign debt, the Fund may be unable to pursue legal action against the sovereign issuer or to realize on collateral securing the debt.

U.S. Government Securities Risk Obligations of certain U.S. Government agencies and instrumentalities are not backed by the full faith and credit of the U.S. Government, and there can be no assurance that the U.S. Government would provide financial support to such agencies and instrumentalities.

Valuation Risk The Fund is subject to the risk of mispricing or improper valuation of its investments, in particular to the extent that its securities are fair valued.

When-Issued, Delayed Delivery, TBA, and Forward Commitment Transaction Risk These transactions may create leverage and involve a risk of loss if the value of the securities declines prior to settlement.

Performance Information

The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows changes in the Fund’s performance from year to year for Class II shares. The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare with those of a broad measure of market performance and an additional index that MML Advisers believes more closely reflects the market segments in which the Fund invests (Bloomberg U.S. Aggregate 1-3 Year Bond Index). Performance shown does not reflect the fees and expenses deducted under the variable life insurance or variable annuity contract through which you invest in the Fund. If these amounts were reflected, returns would be less than those shown. Past performance is not necessarily an indication of how the Fund will perform in the future.

Annual Performance

Class II Shares

Average Annual Total Returns

(for the periods ended December 31, 2024)

​

(1)

Effective July 24, 2024, the Bloomberg U.S. Aggregate Bond Index replaced the Bloomberg U.S. Aggregate 1-3 Year Bond Index as a broad measure of market performance in accordance with new regulatory disclosure requirements. The Fund continues to use the Bloomberg U.S. Aggregate 1-3 Year Bond Index as a supplemental benchmark that MML Advisers believes more closely reflects the market segments in which the Fund invests.

​

MANAGEMENT

Investment Adviser: MML Investment Advisers, LLC (“MML Advisers”)

Subadviser(s): Barings LLC (“Barings”)

Sub-subadviser(s):  Baring International Investment Limited (“BIIL”)

Portfolio Manager(s):

Stephen Ehrenberg, CFA is a Managing Director, portfolio manager for Barings’ Investment Grade Fixed Income Group, and Head of Barings’ North America Investment Grade Credit. He has managed the Fund since November 2019.

Rishi Kapur, CFA is a Managing Director, member of Barings’ Private Placements & Asset Based Finance Group, and Head of Barings’ Securitized Trading. He has managed the Fund since February 2025.

Charles Sanford is a Managing Director and the Head of, and a portfolio manager for, Barings’ Investment Grade Credit Group. He has managed the Fund since December 2020. He previously managed the Fund from inception (May 2010) to November 2017.

PURCHASE AND SALE OF FUND SHARES

Shares of the Fund are generally available to separate investment accounts of variable life insurance and variable annuity contracts offered by companies such as MassMutual. An investor should consult the company issuing the investor’s variable life insurance or variable annuity contract to determine how to make redemptions.

TAX INFORMATION

Dividends and capital gain distributions are paid to the insurance company separate accounts. Variable life insurance and variable annuity contract owners should refer to the variable life insurance or variable annuity product prospectus or consult with their own tax adviser for information regarding the tax consequences of their investment.

PAYMENTS TO INSURANCE COMPANIES AND THEIR AFFILIATES

The Fund is not sold directly to the general public but instead is offered as an underlying investment option for variable insurance contracts. The Fund and its related companies may make payments to the sponsoring insurance company (or its affiliates) or other intermediary for distribution and/or other services. These payments may be a factor that the insurance company considers in

including the Fund as an underlying investment option in the variable insurance contract or may create a conflict of interest by influencing the insurance company or other intermediary to recommend the variable insurance contract over another investment. The prospectus (or other offering document) for your variable insurance contract may contain additional information about these payments.

INVESTMENT OBJECTIVE

The Fund seeks capital appreciation.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. The expenses in the table do not reflect deductions at the separate account level or contract level for any charges that may be incurred under a variable life insurance or variable annuity contract. If these charges were reflected, the fees and expenses in the table would be higher.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in each share class of the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment earns a 5% return each year and that the Fund’s operating expenses are exactly as described in the preceding table. If separate account or variable life insurance or variable annuity contract expenses were included, overall expenses would be higher. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 35% of the average value of its portfolio.

INVESTMENTS, RISKS, AND PERFORMANCE​

Principal Investment Strategies

The Fund invests primarily in common stocks of small-capitalization U.S. companies that the Fund’s subadviser, Invesco Advisers, Inc. (“Invesco Advisers”), believes have favorable business trends or prospects based on fundamental analysis. Under normal circumstances, the Fund invests at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in securities of companies whose market capitalizations at the time of purchase are within the market capitalization range of companies included in the Russell 2000® Index (as of February 28, 2025, between $11.33 million and $49.68 billion). The Fund typically invests most of its assets in equity securities of U.S. companies, but may invest in foreign securities, including emerging market securities; however, it does not currently intend to invest substantially in foreign securities. The Fund generally will not invest more than 15% of its total assets in foreign securities. The Fund may invest in other types of securities such as real estate investment trusts (“REITs”) or other securities that are consistent with its investment objective. The Fund may at times have significant exposure to one or more industries or sectors. The Fund may hold a portion of its assets in cash or cash equivalents.

Invesco Advisers uses fundamental research to select securities for the Fund’s portfolio. While the process may change over time or vary in particular cases, in general the selection process currently uses a fundamental approach in analyzing issuers on factors such as a company’s financial performance, competitive strength and prospects, industry position, and business model and management strength. Industry outlook, market trends, and general economic conditions may also be considered.

Invesco Advisers aims to maintain a broad diversification across all major economic sectors. In constructing the portfolio, Invesco Advisers seeks to limit exposure to so-called “top-down” or “macro” risks, such as overall stock market movements, economic cycles, and interest rate or currency fluctuations. Instead, Invesco Advisers seeks to add value by selecting individual securities that it believes have superior company-specific fundamental attributes or relative valuations that

they expect to outperform their industry and sector peers. This is commonly referred to as a “bottom-up” approach to portfolio construction.

Invesco Advisers considers stock rankings, benchmark weightings, and capitalization outlooks in determining security weightings for individual issuers. Invesco Advisers might sell a security if, for example, in its judgment, a stock’s price is approaching its target, a company’s competitive position deteriorates, a company’s management is performing poorly, or more attractive alternative investment ideas have been identified.

Principal Risks

The following are the Principal Risks of the Fund. The value of your investment in the Fund could go down as well as up. You can lose money by investing in the Fund. Certain risks relating to instruments and strategies used in the management of the Fund are placed first. The significance of any specific risk to an investment in the Fund will vary over time, depending on the composition of the Fund’s portfolio, market conditions, and other factors. You should read all of the risk information presented below carefully, because any one or more of these risks may result in losses to the Fund.

Equity Securities Risk Although stocks may have the potential to outperform other asset classes over the long term, their prices tend to fluctuate more dramatically over the shorter term. These movements may result from factors affecting individual companies, or from broader influences like changes in interest rates, market conditions, or investor confidence, or announcements of economic, political, or financial information.

Small and Mid-Cap Company Risk Market risk and liquidity risk are particularly pronounced for securities of small and medium-sized companies, which may trade less frequently and in smaller volumes than more widely-held securities, and may fluctuate in price more than other securities. Their shares can be less liquid than those of larger companies, especially during market declines. Small and medium-sized companies may have limited product lines, markets, or financial resources and may be dependent on a limited management group; they may have been recently organized and have little or no track record of success.

Foreign Investment Risk; Emerging Markets Risk; Currency Risk Investments in securities of foreign issuers, securities of companies with significant foreign exposure, and foreign currencies can involve

additional risks relating to market, industry, political, regulatory, public health, and other conditions. Political, social, diplomatic, and economic developments, U.S. and foreign government action, or threat thereof, such as the imposition of currency or capital blockages, controls, or tariffs, economic and trade sanctions or embargoes, security trading suspensions, entering or exiting trade or other intergovernmental agreements, or the expropriation or nationalization of assets in a particular country, can cause dramatic declines in certain or all securities with exposure to that country and other countries. Sanctions, or the threat of sanctions, may cause volatility in regional and global markets and may negatively impact the performance of various sectors and industries, as well as companies in other countries, which could have a negative effect on the performance of the Fund. In the event of nationalization, expropriation, confiscation, or other government action, intervention, or restriction, the Fund could lose its entire investment in a particular foreign issuer or country. There may be quotas or other limits on the ability of the Fund (or clients of the Fund’s investment adviser or subadviser) to invest or maintain investments in securities of issuers in certain countries. Enforcing legal rights can be more difficult, costly, and limited in certain foreign countries and with respect to certain types of investments, and can be particularly difficult against foreign governments. Because non-U.S. securities are normally denominated and traded in currencies other than the U.S. dollar, the value of the Fund’s assets may be affected favorably or unfavorably by changes in currency exchange rates, exchange control regulations, and restrictions or prohibitions on the repatriation of non-U.S. currencies. Income and gains with respect to investments in certain countries may be subject to withholding and other taxes. There may be less information publicly available about a non-U.S. company than about a U.S. company, and many non-U.S. companies are not subject to accounting, auditing, and financial reporting standards, regulatory framework and practices comparable to those in the U.S. The securities of some non-U.S. companies, especially those in emerging markets, are less liquid and at times more volatile than securities of comparable U.S. companies. Emerging markets securities are subject to greater risks than securities issued in developed foreign markets, including less liquidity, less stringent investor protection and disclosure standards, less reliable settlement practices, greater price volatility, higher

relative rates of inflation, greater political, economic, and social instability, greater custody and operational risks, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater volatility in currency exchange rates, and are more susceptible to environmental problems. Many emerging market countries are highly reliant on international trade and exports, including the export of commodities. Their economies may be significantly impacted by fluctuations in commodity prices and the global demand for certain commodities. In addition, pandemics and outbreaks of contagious diseases may exacerbate pre-existing problems in emerging market countries with less established health care systems. Frontier markets, a subset of emerging markets, generally have smaller economies and less mature capital markets than emerging markets. As a result, the risks of investing in emerging market countries are magnified in frontier market countries. Frontier markets are more susceptible to having abrupt changes in currency values, less mature markets and settlement practices, and lower trading volumes that could lead to greater price volatility and illiquidity. Non-U.S. transaction costs, such as brokerage commissions and custody costs, may be higher than in the United States. In addition, foreign markets can react differently to market, economic, industry, political, regulatory, geopolitical, public health, and other conditions than the U.S. market. The Fund may invest in foreign securities known as depositary receipts. Investments in depositary receipts are subject to the same risks as direct investment in foreign securities, which include market, political, currency, and regulatory risks.

Growth Company Risk The prices of growth securities are often highly sensitive to market fluctuations because of their heavy dependence on future earnings or cash flow expectations, and can be more volatile than the market in general.

Value Company Risk The value investment approach entails the risk that the market will not recognize a security’s intrinsic value for a long time, or that a stock the investment adviser or subadviser judges to be undervalued may actually be appropriately priced.

Cash Position Risk If the Fund holds a significant portion of its assets in cash or cash equivalents, its investment returns may be adversely affected and the Fund may not achieve its investment objective.

Liquidity Risk Certain securities may be difficult (or impossible) to sell or certain positions may be difficult to close out at a desirable time and price, and the Fund may be required to hold an illiquid investment that is declining in value, or it may be required to sell certain illiquid investments at a price or time that is not advantageous in order to meet redemptions or other cash needs. Some securities may be subject to restrictions on resale. There can be no assurance that there will be a liquid market for instruments held by the Fund at any time. The Fund may not receive the proceeds from the sale of certain investments for an extended period.

Management and Operational Risk The Fund relies on the manager’s investment analysis and its selection of investments to achieve its investment objective, and the Fund is subject to the risk that the manager’s assessment of an investment is wrong. There can be no assurance that the Fund will achieve the intended results and the Fund may incur significant losses. The Fund also runs the risk that deficiencies in the investment adviser’s, subadviser’s, or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

Market Risk The value of the Fund’s portfolio securities may decline, at times sharply and unpredictably, as a result of unfavorable market-induced changes affecting particular industries, sectors, or issuers. Stock and bond markets can decline significantly in response to issuer, market, economic, industry, political, regulatory, geopolitical, public health, and other conditions, as well as investor perceptions of these conditions. The Fund is subject to risks affecting issuers, such as management performance, financial leverage, industry problems, and reduced demand for goods or services.

REIT Risk Investments in REITs may be subject to risks similar to those associated with direct investment in real estate, as well as additional risks associated with equity investments. As a shareholder in a REIT, the Fund, and indirectly the Fund’s shareholders, would bear its ratable share of the REIT’s expenses and would at the same time continue to pay its own fees and expenses.

Sector Risk The Fund may allocate more of its assets to particular industries or to particular economic, market, or industry sectors than to others. This could increase the volatility of the Fund’s portfolio, and the Fund’s performance may

be more susceptible to developments affecting issuers in those industries or sectors than if the Fund invested more broadly.

Valuation Risk The Fund is subject to the risk of mispricing or improper valuation of its investments, in particular to the extent that its securities are fair valued.

Performance Information

The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows changes in the Fund’s performance from year to year for Initial Class shares. The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare with those of a broad measure of market performance and an additional index that MML Advisers believes more closely reflects the market segments in which the Fund invests (Russell 2000 Index). Performance shown does not reflect the fees and expenses deducted under the variable life insurance or variable annuity contract through which you invest in the Fund. If these amounts were reflected, returns would be less than those shown. Past performance is not necessarily an indication of how the Fund will perform in the future.

Annual Performance

Initial Class Shares

Average Annual Total Returns

(for the periods ended December 31, 2024)

​

(1)

Effective July 24, 2024, the Russell 3000 Index replaced the Russell 2000 Index as a broad measure of market performance in accordance with new regulatory disclosure requirements. The Fund continues to use the Russell 2000 Index as a supplemental benchmark that MML Advisers believes more closely reflects the market segments in which the Fund invests.

​

MANAGEMENT

Investment Adviser: MML Investment Advisers, LLC (“MML Advisers”)

Subadviser(s): Invesco Advisers, Inc. (“Invesco Advisers”)

Portfolio Manager(s):

Joy Budzinski is a Portfolio Manager at Invesco Advisers. She has managed the Fund since April 2013.

Magnus Krantz is a Portfolio Manager at Invesco Advisers. He has managed the Fund since April 2013.

Raman Vardharaj, CFA is a Portfolio Manager at Invesco Advisers. He has managed the Fund since May 2009.

Adam Weiner is a Co-Lead Portfolio Manager at Invesco Advisers. He has managed the Fund since April 2013.

Matthew P. Ziehl, CFA is a Co-Lead Portfolio Manager at Invesco Advisers. He has managed the Fund since May 2009.

PURCHASE AND SALE OF FUND SHARES

Shares of the Fund are generally available to separate investment accounts of variable life insurance and variable annuity contracts offered by companies such as MassMutual. An investor should consult the company issuing the investor’s variable life insurance or variable annuity contract to determine how to make redemptions.

TAX INFORMATION

Dividends and capital gain distributions are paid to the insurance company separate accounts. Variable life insurance and variable annuity contract owners should refer to the variable life insurance or variable annuity product prospectus or

consult with their own tax adviser for information regarding the tax consequences of their investment.

PAYMENTS TO INSURANCE COMPANIES AND THEIR AFFILIATES

The Fund is not sold directly to the general public but instead is offered as an underlying investment option for variable insurance contracts. The Fund and its related companies may make payments to the sponsoring insurance company (or its affiliates) or other intermediary for distribution

and/or other services. These payments may be a factor that the insurance company considers in including the Fund as an underlying investment option in the variable insurance contract or may create a conflict of interest by influencing the insurance company or other intermediary to recommend the variable insurance contract over another investment. The prospectus (or other offering document) for your variable insurance contract may contain additional information about these payments.

INVESTMENT OBJECTIVE

This Fund seeks current income consistent with preservation of capital and liquidity.

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund. The expenses in the table do not reflect deductions at the separate account level or contract level for any charges that may be incurred under a variable life insurance or variable annuity contract. If these charges were reflected, the fees and expenses in the table would be higher.

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It assumes that you invest $10,000 in each share class of the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment earns a 5% return each year and that the Fund’s operating expenses are exactly as described in the preceding table. If separate account or variable life insurance or variable annuity contract expenses were included, overall expenses would be higher. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

INVESTMENTS, RISKS, AND PERFORMANCE​

Principal Investment Strategies

The Fund normally invests at least 99.5% of its total assets in cash, U.S. Government securities, and/or repurchase agreements fully collateralized by cash or U.S. Government securities.

In managing the Fund, the Fund’s subadviser, Barings LLC (“Barings”), intends to comply with Rule 2a-7 under the Investment Company Act of 1940, as amended (the “1940 Act”), which sets

forth the requirements for money market funds regarding credit quality, diversification, liquidity, and maturity. The Fund seeks to maintain, but does not guarantee, a stable $1.00 share price.

Under normal circumstances, the Fund invests at least 80% of its net assets in U.S. Government securities and repurchase agreements that are fully collateralized by U.S. Government securities. U.S. Government securities are high-quality securities issued or guaranteed by the U.S. Treasury or by an agency or instrumentality of the U.S. Government. U.S. Government securities may be backed by the full faith and credit of the U.S. Treasury, the right to borrow from the U.S. Treasury, or the agency or instrumentality issuing or guaranteeing the security. Certain issuers of U.S. Government securities, including Fannie Mae, Freddie Mac, and the Federal Home Loan Banks, are sponsored or chartered by Congress but their securities are neither issued nor guaranteed by the U.S. Treasury.

Principal Risks

You could lose money by investing in the Fund. Although the Fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. An investment in the Fund is not a bank account and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The Fund’s sponsor is not required to reimburse the Fund for losses, and you should not expect that the sponsor will provide financial support to the Fund at any time, including during periods of market stress.

Certain risks relating to instruments and strategies used in the management of the Fund are placed first. The significance of any specific risk to an investment in the Fund will vary over time, depending on the composition of the Fund’s portfolio, market conditions, and other factors. You should read all of the risk information presented below carefully, because any one or more of these risks may result in losses to the Fund.

Money Market Instruments Risk The value of a money market instrument typically will decline during periods of rising interest rates, and can also decline in response to changes in the financial condition of the issuer, borrower, counterparty, or underlying collateral assets, or changes in market, economic, industry, political, regulatory, public

health, and other conditions affecting a particular type of security or issuer or fixed income securities generally.

U.S. Government Securities Risk Obligations of certain U.S. Government agencies and instrumentalities are not backed by the full faith and credit of the U.S. Government, and there can be no assurance that the U.S. Government would provide financial support to such agencies and instrumentalities.

Repurchase Agreement Risk  These transactions must be fully collateralized, but involve credit risk to a Fund if the other party should default on its obligation and the Fund is delayed or prevented from recovering the collateral.

Credit Risk Credit risk is the risk that an issuer, guarantor, or liquidity provider of a fixed income security held by the Fund may be unable or unwilling, or may be perceived (whether by market participants, ratings agencies, pricing services or otherwise) as unable or unwilling, to make timely principal and/or interest payments, or to otherwise honor its obligations. The Fund may also be exposed to the credit risk of its counterparty to repurchase agreements, reverse repurchase agreements, swap transactions, and other derivatives transactions, and to the counterparty’s ability or willingness to perform in accordance with the terms of the transaction. The value of such transactions to the Fund will depend on the willingness and ability of the counterparty to perform its obligations, including among other things the obligation to return collateral or margin to the Fund. If a counterparty becomes bankrupt or otherwise fails to perform its obligations under a derivative contract due to financial difficulties, the Fund may experience significant delays in obtaining any recovery under the derivative contract in a bankruptcy or other reorganization proceeding. The Fund may obtain only a limited recovery or may obtain no recovery in such circumstances.

Inflation Risk The value of assets or income from the Fund’s investments will be less in the future as inflation decreases the value of money. As inflation increases, the value of the Fund’s assets can decline as can the value of the Fund’s distributions. Inflation rates may change frequently and drastically as a result of various factors, including unexpected shifts in the domestic or global economy (or expectations that such policies will change), and the Fund’s investments may not keep pace with inflation, which may result in losses to the Fund’s investors.

Liquidity Risk Certain securities may be difficult (or impossible) to sell or certain positions may be difficult to close out at a desirable time and price, and the Fund may be required to hold an illiquid investment that is declining in value, or it may be required to sell certain illiquid investments at a price or time that is not advantageous in order to meet redemptions or other cash needs. Some securities may be subject to restrictions on resale. There can be no assurance that there will be a liquid market for instruments held by the Fund at any time. The Fund may not receive the proceeds from the sale of certain investments for an extended period.

Management and Operational Risk The Fund relies on the manager’s investment analysis and its selection of investments to achieve its investment objective, and the Fund is subject to the risk that the manager’s assessment of an investment is wrong. There can be no assurance that the Fund will achieve the intended results and the Fund may incur significant losses. The Fund also runs the risk that deficiencies in the investment adviser’s, subadviser’s, or another service provider’s internal systems or controls will cause losses for the Fund or impair Fund operations.

Market Risk The value of the Fund’s portfolio securities may decline, at times sharply and unpredictably, as a result of unfavorable market-induced changes affecting particular industries, sectors, or issuers. Stock and bond markets can decline significantly in response to issuer, market, economic, industry, political, regulatory, geopolitical, public health, and other conditions, as well as investor perceptions of these conditions. The Fund is subject to risks affecting issuers, such as management performance, financial leverage, industry problems, and reduced demand for goods or services.

Prepayment Risk Prepayment risk is the risk that principal of a debt obligation will be repaid at a faster rate than anticipated. In such a case, a Fund may lose the benefit of a favorable interest rate for the remainder of the term of the security in question, and may only be able to reinvest the amount of the prepayment at a less favorable rate.

Valuation Risk The Fund is subject to the risk of mispricing or improper valuation of its investments, in particular to the extent that its securities are fair valued.

Performance Information

The following bar chart and table provide some indication of the risks of investing in the Fund. The bar chart shows changes in the Fund’s performance from year to year for Initial Class shares. The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare with those of a broad measure of market performance and an additional index that MML Advisers believes more closely reflects the market segments in which the Fund invests (FTSE 3 Month US T Bill Index). The Fund’s name, investment objective, and investment strategy changed on May 1, 2016 when the Fund changed from a money market fund to a government money market fund. Performance results shown were achieved when the Fund could invest in types of securities that it is no longer able to hold. Future performance of the Fund may be lower as a result. Performance shown does not reflect the fees and expenses deducted under the variable life insurance or variable annuity contract through which you invest in the Fund. If these amounts were reflected, returns would be less than those shown. Past performance is not necessarily an indication of how the Fund will perform in the future.

Annual Performance

Initial Class Shares

Average Annual Total Returns

(for the periods ended December 31, 2024)

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(1)

Effective July 24, 2024, the Bloomberg U.S. Aggregate Bond Index replaced the FTSE 3 Month US T Bill Index as a broad measure of market performance in accordance with new regulatory disclosure requirements. The Fund continues to use the FTSE 3 Month US T Bill Index as a supplemental benchmark that MML Advisers believes more closely reflects the market segments in which the Fund invests.

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MANAGEMENT

Investment Adviser: MML Investment Advisers, LLC (“MML Advisers”)

Subadviser(s): Barings LLC (“Barings”)

Portfolio Manager(s):

Adam Cash is a Director and member of Barings’ Investment Grade Fixed Income Group. He has managed the Fund since May 2022.

Scott Simler is a Senior Director and member of Barings’ Trading Solutions Group. He has managed the Fund since July 2009.

PURCHASE AND SALE OF FUND SHARES

Shares of the Fund are generally available to separate investment accounts of variable life insurance and variable annuity contracts offered by companies such as MassMutual. An investor should consult the company issuing the investor’s variable life insurance or variable annuity contract to determine how to make redemptions.

TAX INFORMATION

Dividends and capital gain distributions are paid to the insurance company separate accounts. Variable life insurance and variable annuity contract owners should refer to the variable life insurance or variable annuity product prospectus or consult with their own tax adviser for information regarding the tax consequences of their investment.

PAYMENTS TO INSURANCE COMPANIES AND THEIR AFFILIATES

The Fund is not sold directly to the general public but instead is offered as an underlying investment option for variable insurance contracts. The Fund and its related companies may make payments to the sponsoring insurance company (or its affiliates) or other intermediary for distribution and/or other services. These payments may be a factor that the insurance company considers in

including the Fund as an underlying investment option in the variable insurance contract or may create a conflict of interest by influencing the insurance company or other intermediary to recommend the variable insurance contract over another investment. The prospectus (or other offering document) for your variable insurance contract may contain additional information about these payments.

Except as otherwise stated, references in this section to “the Funds” or “a Fund” may relate to a Fund, one or more investment companies or other pooled investment products in which a Fund may invest, including among others underlying exchange-traded funds (“ETFs”) in which the MML Blend Fund, MML iShares 60/40 Allocation Fund, or MML iShares 80/20 Allocation Fund may invest, or both.

Changes to Investment Objectives and Strategies. 

Each Fund’s investment objective and strategies are non-fundamental and may be changed by the Board of Trustees (the “Trustees”) of the MML Series Investment Fund II (the “Trust”) without shareholder approval.

Note Regarding Percentage Limitations. 

All percentage limitations on investments in this Prospectus will apply at the time of investment, and will not be considered violated unless an excess or deficiency occurs or exists immediately after and as a result of the investment, except as may be otherwise specified in the Statement of Additional Information (“SAI”). (As a result, the actual investments making up a Fund’s portfolio may not at a particular time comport with any such limitation due to increases or decreases in the values of securities held by the Fund.) However, if, through a change in values, net assets, or other circumstances, a Fund were in a position where more than 15% of its net assets was invested in illiquid securities, the Fund would take appropriate orderly steps, as deemed necessary, to protect liquidity. With respect to a Fund whose name suggests that the Fund focuses its investments in a particular type of investment or investments, or in investments in a particular industry or group of industries, and that has adopted a policy under Rule 35d-1 under the 1940 Act, such Fund’s policy to invest at least 80% of its net assets in certain investments may be changed by the Trustees upon at least 60 days’ prior written notice to shareholders.

Credit Ratings. 

Security ratings are determined at the time of investment based on ratings published by nationally recognized statistical rating organizations; if a security is not rated, it will be deemed to have the same rating as a security determined by the investment adviser or subadviser to be of

comparable quality. Unless otherwise stated, if a security is rated by more than one nationally recognized statistical rating organization, the highest rating is used. The Fund may retain any security whose rating has been downgraded after purchase.

Duration. 

Duration is a measure of the expected life of a debt security that is used to determine the sensitivity of the security’s value to changes in interest rates. The longer a security’s duration, the more sensitive it will be to changes in interest rates. For example, if interest rates rise by 1%, the value of a debt security with a duration of two years would be expected to decline 2% and the value of a debt security with a duration of four years would be expected to decline 4%. Unlike the maturity of a debt security, which measures only the time until final payment is due, duration takes into account the time until all payments of interest and principal on a security are expected to be made, including how these payments are affected by prepayments and by changes in interest rates. Determining duration may involve estimates of future economic parameters, which may vary from actual future values.

Leverage. 

Leverage generally has the effect of increasing the amount of loss or gain a Fund might realize, and may increase volatility in the value of a Fund’s investments. Adverse changes in the value or level of the underlying asset, rate, or index may result in a loss substantially greater than the amount invested in the derivative itself.

Temporary Defensive Positions. 

At times, a Fund’s investment adviser or subadviser may determine that market conditions make pursuing a Fund’s basic investment strategy inconsistent with the best interests of its shareholders. At such times, the investment adviser or subadviser may (but will not necessarily), without notice, temporarily use alternative strategies primarily designed to reduce fluctuations in the values of a Fund’s assets. In implementing these defensive strategies, a Fund may hold assets without limit in cash and cash equivalents and in other investments that the investment adviser or subadviser believes to be consistent with the Fund’s best interests. If such a temporary defensive strategy is implemented, a Fund may not achieve its investment objective.

Portfolio Turnover. 

Changes are made in a Fund’s portfolio whenever the investment adviser or subadviser believes such changes are desirable. Portfolio turnover rates are generally not a factor in making buy and sell decisions. A high portfolio turnover rate will result in higher costs from brokerage commissions, dealer-mark-ups, bid-ask spreads, and other transaction costs. Such costs are not reflected in the Funds’ Total Annual Fund Operating Expenses set forth in the fee tables but do have the effect of reducing a Fund’s investment return.

Non-Principal Investments; Use of Derivatives; Securities Loans; Repurchase Agreements. 

A Fund may hold investments that are not included in its principal investment strategies. These non-principal investments are described in the SAI or below under “Additional Information Regarding Principal Risks.” A Fund also may choose not to invest in certain securities described in this Prospectus and in the SAI, even though it has the ability to do so. Certain Funds may engage in transactions involving derivatives as part of their principal investment strategies; the disclosures of the principal investment strategies of those Funds include specific references to those derivatives transactions. Any of the other Funds may engage in derivatives transactions not as part of their principal investment strategies, and Funds that may use certain derivatives as part of their principal investment strategies may use other derivatives (not as part of their principal investment strategies), as well. A Fund may use derivatives for hedging purposes, as a substitute for direct investment, to earn additional income, to adjust portfolio characteristics, including duration (interest rate volatility), to gain exposure to securities or markets in which it might not be able to invest directly, to provide asset/liability management, or to take long or short positions on one or more indexes, securities, or foreign currencies. If a Fund takes a short position with respect to a particular index, security, or currency, it will lose money if the index, security, or currency appreciates in value, or an expected credit or other event that might affect the value of the index, security, or currency fails to occur. Losses could be significant. Derivatives transactions may include, but are not limited to, foreign currency exchange transactions, options, futures contracts, interest rate swaps, interest rate futures contracts, forward contracts, total return swaps, credit default swaps, and hybrid instruments. A Fund may use derivatives to create investment leverage. See

“Additional Information Regarding Principal Risks,” below, and the SAI for more information regarding those transactions.

A Fund, with the exception of the MML U.S. Government Money Market Fund, may make loans of portfolio securities to broker-dealers and other financial intermediaries of up to 33% of its total assets, and may enter into repurchase agreements. These transactions must be fully collateralized at all times, but involve some risk to a Fund if the other party should default on its obligation and the Fund is delayed or prevented from recovering the collateral, or if the Fund is required to return collateral to a borrower at a time when it may realize a loss on the investment of that collateral. Any losses from the investment of cash collateral received by the Fund will be for the Fund’s account and may exceed any income the Fund receives from its securities lending activities. A repurchase agreement is a transaction in which a Fund purchases a security from a seller, subject to the obligation of the seller to repurchase that security from the Fund at a higher price. A Fund may enter into securities loans and repurchase agreements as a non-principal investment strategy.

Foreign Securities. 

The globalization and integration of the world economic system and related financial markets have made it increasingly difficult to define issuers geographically. Accordingly, the Funds intend to construe geographic terms such as “foreign,” “non-U.S.,” “European,” “Latin American,” “Asian,” and “emerging markets” in the manner that affords to the Funds the greatest flexibility in seeking to achieve the investment objective(s) of the relevant Fund. Specifically, unless otherwise stated, in circumstances where the investment objective and/or strategy is to invest (a) exclusively in “foreign securities,” “non-U.S. securities,” “European securities,” “Latin American securities,” “Asian securities,” or “emerging markets” ​(or similar directions) or (b) at least some percentage of the Fund’s assets in foreign securities, etc., the Fund will take the view that a security meets this description so long as the issuer of a security is tied economically to the particular country or geographic region indicated by words of the relevant investment objective and/or strategy (the “Relevant Language”). For these purposes the issuer of a security is deemed to have that tie if:

(i) the issuer is organized under the laws of the country or a country within the geographic region suggested by the Relevant Language or maintains its principal place of business in that country or region; or

(ii) the securities are traded principally in the country or region suggested by the Relevant Language; or

(iii) the issuer, during its most recent fiscal year, derived at least 50% of its revenues or profits from goods produced or sold, investments made, or services performed in the country or region suggested by the Relevant Language or has at least 50% of its assets in that country or region.

In addition, the Funds intend to treat derivative securities (e.g., call options) for this purpose by reference to the underlying security. Conversely, if the investment objective and/or strategy of a Fund limits the percentage of assets that may be invested in “foreign securities,” etc. or prohibits such investments altogether, a Fund intends to categorize securities as “foreign,” etc. only if the security possesses all of the attributes described above in clauses (i), (ii), and (iii).

MML Invesco Discovery Large Cap Fund.  

MML Advisers has agreed to cap the fees and expenses of the Fund (other than extraordinary legal and other expenses, Acquired Fund Fees and Expenses, interest expense, expenses related to borrowings, securities lending, leverage, taxes, and brokerage, short sale dividend and loan expense, or other non-recurring or unusual expenses such as organizational expenses and shareholder meeting expenses, as applicable) through April 30, 2028, to the extent that Total Annual Fund Operating Expenses after Expense Reimbursement would otherwise exceed 0.80% and 1.05% for Class II and Service Class I shares, respectively. The agreement can only be terminated by mutual consent of the Board of Trustees on behalf of the Fund and MML Advisers.

MML Invesco Discovery Mid Cap Fund.  

MML Advisers has agreed to cap the fees and expenses of the Fund (other than extraordinary legal and other expenses, Acquired Fund Fees and Expenses, interest expense, expenses related to

borrowings, securities lending, leverage, taxes, and brokerage, short sale dividend and loan expense, or other non-recurring or unusual expenses such as organizational expenses and shareholder meeting expenses, as applicable) through April 30, 2028, to the extent that Total Annual Fund Operating Expenses after Expense Reimbursement would otherwise exceed 0.85% and 1.10% for Class II and Service Class I shares, respectively. The agreement can only be terminated by mutual consent of the Board of Trustees on behalf of the Fund and MML Advisers.

MML Managed Bond Fund. 

MML Advisers has agreed to cap the fees and expenses of the Fund (other than extraordinary legal and other expenses, Acquired Fund Fees and Expenses, interest expense, expenses related to borrowings, securities lending, leverage, taxes, and brokerage, short sale dividend and loan expense, or other non-recurring or unusual expenses such as organizational expenses and shareholder meeting expenses, as applicable) through April 30, 2027, to the extent that Total Annual Fund Operating Expenses after Expense Reimbursement would otherwise exceed 0.57% and 0.82% for Initial Class and Service Class shares, respectively. The agreement can only be terminated by mutual consent of the Board of Trustees on behalf of the Fund and MML Advisers.

MML U.S. Government Money Market Fund. 

The Fund’s 7-day yield on December 31, 2024 was 4.05%. To obtain the Fund’s current 7-day yield information, please call 1-888-309-3539. MML Advisers has agreed to voluntarily waive some or all of its management fees and, if necessary, reimburse some or all of the Fund’s other expenses, in an attempt to allow the Fund to maintain a 1-day yield of at least approximately 0.00%. MML Advisers may amend or discontinue this waiver at any time without advance notice.

A Fund, by itself, generally is not intended to provide a complete investment program. Investment in the Funds is intended to serve as part of a diversified portfolio of investments. An investment in a Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

The value of your investment in a Fund changes with the values of the investments in the Fund’s portfolio. Many things can affect those values. Factors that may have an important or significant effect on a particular Fund’s portfolio as a whole are called “Principal Risks.” The Principal Risks of each Fund are identified in the foregoing Fund Summaries and are described in this section. Certain Funds may be more susceptible to some risks than others. Although the Funds strive to reach their stated goals, they cannot offer guaranteed results. The value of your investment in a Fund could go down as well as up. You can lose money by investing in the Funds. References in this section to a Fund’s subadviser may include any sub-subadvisers as applicable. Except as otherwise stated, references in this section to “the Funds” or “a Fund” may relate to a Fund, one or more investment companies or other pooled investment products in which a Fund may invest, including among others underlying ETFs in which the MML Blend Fund, MML iShares 60/40 Allocation Fund, or MML iShares 80/20 Allocation Fund may invest, or both.

The SAI contains further information about the Funds, their investments and their related risks.

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Allocation Risk 

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There is no assurance that allocation decisions will result in the desired performance effects. There is a risk that MML Advisers’ or BlackRock’s, as applicable, evaluations and assumptions regarding asset classes or ETFs may be incorrect in view of actual market conditions. The requirement that substantially all of the MML Blend Fund’s, MML iShares 60/40 Allocation Fund’s, and MML iShares 80/20 Allocation Fund’s assets be invested in

ETFs advised by an affiliate of BlackRock as noted in the Fund’s “Principal Investment Strategies” may adversely affect Fund performance.

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Bank Loans Risk 

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Many of the risks associated with bank loans are similar to the risks of investing in below investment grade debt securities, although bank loans are typically (though not always) senior and secured, while below investment grade debt securities or investments are often subordinated and unsecured. Senior loans are subject to the risk that a court could subordinate a senior loan, which typically holds the most senior position in the issuer’s capital structure, to presently existing or future indebtedness or take other action detrimental to the holders of senior loans. Changes in the financial condition of the borrower or economic conditions or other circumstances may reduce the capacity of the borrower to make principal and interest payments on such instruments and may lead to defaults. The value of any collateral securing a bank loan may decline after a Fund invests, and there is a risk that the value of the collateral may not be sufficient to cover the amount owed to the Fund. In addition, collateral securing a loan may be found invalid, may be used to pay other outstanding obligations of the borrower under applicable law, or may be difficult to sell. In the event that a borrower defaults, a Fund’s access to the collateral may be limited by bankruptcy and other insolvency laws. There is also the risk that the collateral may be difficult to liquidate, or that a majority of the collateral may be illiquid. In addition, some loans may be unsecured. Unsecured loans generally present a greater risk of loss to the Fund if the issuer defaults. In some cases, the Fund may rely on a third party to administer its interest in a loan, and so is subject to the risk that the third party will be unwilling or unable to perform its obligations. The Fund may invest in a loan by purchasing an indirect interest in the loan held by a third party. In

that case, the Fund will be subject to both the credit risk of the borrower and of the third party, and the Fund may be unable to realize some or all of the value of its interest in the loan in the event of the insolvency of the third party. The settlement time for certain loans is longer than the settlement time for many other types of investments, and the Fund may not receive the payment for a loan sold by it until well after the sale; that cash would be unavailable for payment of redemption proceeds or for reinvestment. Interests in some bank loans may not be readily marketable and may be subject to restrictions on resale. In some cases, negotiations involved in disposing of indebtedness may require weeks to complete. Consequently, some indebtedness may be difficult or impossible to dispose of readily at what the Fund believes to be a fair price. Some bank loans may be illiquid, and bank loans generally tend to be less liquid than many other debt securities. The lack of a liquid secondary market may make it more difficult for the Fund to assign a value to such instruments for purposes of valuing the Fund’s portfolio and calculating its net asset value (“NAV”). Some loans may not be considered “securities” for certain purposes under the federal securities laws, and purchasers, such as the Fund, therefore may not be entitled to rely on the anti-fraud protections of the federal securities laws.

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Below Investment Grade Debt Securities Risk 

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Below investment grade debt securities, which are also known as “junk” or “high yield” bonds, and comparable unrated securities in which a Fund may invest, have speculative characteristics, and changes in economic conditions, the financial condition of the issuer, and/or an unanticipated rise in interest rates or other circumstances are more likely to lead to a weakened capacity to make principal and interest payment than in the case of higher grade securities. Below investment grade debt securities involve greater volatility of price and yield and greater risk of loss of principal and interest than do higher quality securities. In the past, economic downturns or increases in interest rates have, under certain circumstances, resulted in a higher incidence of default by the issuers of these instruments and are likely to do so in the future, especially in the case of highly leveraged issuers. The

prices for these instruments may be affected by legislative and regulatory developments. Some below investment grade debt securities are issued in connection with management buy-outs and other highly leveraged transactions, and may entail substantial risk of delays in payments of principal or interest or of defaults. The inability (or perceived inability) of issuers to make timely payment of interest and principal would likely make the values of securities held by the Fund more volatile and could limit the Fund’s ability to sell its securities at prices approximating the values the Fund has placed on such securities. In the absence of a liquid trading market for securities held by it, a Fund at times may be unable to establish the fair value of such securities. To the extent a Fund invests in securities in the lower rating categories, the achievement of the Fund’s goals is more dependent on the Fund investment adviser’s or subadviser’s investment analysis than would be the case if the Fund were investing in securities in the higher rating categories. Securities that are rated CCC or below by Standard & Poor’s or Caa or below by Moody’s Investors Service, Inc. are generally regarded by the rating agencies as having extremely poor prospects of ever attaining any real investment standing.

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Cash Position Risk 

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A Fund may hold a significant portion of its assets in cash or cash equivalents at the sole discretion of the Fund’s investment adviser or subadviser, based on such factors as it may consider appropriate under the circumstances. The portion of a Fund’s assets invested in cash and cash equivalents may at times exceed 25% of the Fund’s net assets. To the extent a Fund holds a significant portion of its assets in cash or cash equivalents, its investments returns may be adversely affected and the Fund may not achieve its investment objective.

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Convertible Securities Risk 

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Convertible securities are bonds, debentures, notes or other debt securities that may be converted at either a stated price or stated rate into shares of common or preferred stock (or cash or other securities of equivalent value), and so are subject to the risks of investments in both debt securities and equity securities. The price of a convertible security may change

in response to changes in price of the underlying equity security, the credit quality of the issuer, and interest rates. Due to the conversion feature, convertible debt securities generally yield less than non-convertible securities of similar credit quality and maturity. The values of convertible securities may be interest-rate sensitive and tend to decline as interest rates rise and to rise when interest rates fall. A Fund may invest at times in securities that have a mandatory conversion feature, pursuant to which the securities convert automatically into stock at a specified date and conversion ratio, or that are convertible at the option of the issuer. When conversion is not at the option of the holder, a Fund may be required to convert the security into the underlying stock even at times when the value of the underlying common stock has declined substantially or it would otherwise be disadvantageous to do so.

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Credit Risk 

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Credit risk is the risk that an issuer, guarantor, or liquidity provider of a fixed income security held by a Fund may be unable or unwilling, or may be perceived (whether by market participants, ratings agencies, pricing services or otherwise) as unable or unwilling, to make timely principal and/or interest payments, or to otherwise honor its obligations. It includes the risk that the security will be downgraded by a credit rating agency; generally, lower credit quality issuers present higher credit risks. An actual or perceived decline in creditworthiness of an issuer of a fixed income security held by the Fund may result in a decrease in the value of the security. It is possible that the ability of an issuer to meet its obligations will decline substantially during the period when the Fund owns securities of the issuer or that the issuer will default on its obligations or that the obligations of the issuer will be limited or restructured. The credit rating assigned to any particular investment does not necessarily reflect the issuer’s current financial condition and does not reflect an assessment of an investment’s volatility or liquidity. Securities rated in the lowest category of investment grade are considered to have speculative characteristics. In addition, below investment grade debt securities (i.e., “junk” or “high yield” bonds) involve greater credit risk, are more volatile, involve greater risk of price

declines and may be more susceptible to economic downturn than investment grade securities. If a security held by the Fund loses its rating or its rating is downgraded, the Fund may nonetheless continue to hold the security in the discretion of the investment adviser or subadviser. In the case of asset-backed or mortgage-related securities, changes in the actual or perceived ability of the obligors on the underlying assets or mortgages may affect the values of those securities.

The Fund may also be exposed to the credit risk of its counterparty to repurchase agreements, reverse repurchase agreements, swap transactions, and other derivatives transactions, and to the counterparty’s ability or willingness to perform in accordance with the terms of the transaction. The value of such transactions to the Fund will depend on the willingness and ability of the counterparty to perform its obligations, including among other things the obligation to return collateral or margin to the Fund. If a counterparty becomes bankrupt or otherwise fails to perform its obligations under a derivative contract due to financial difficulties, the Fund may experience significant delays in obtaining any recovery under the derivative contract in a bankruptcy or other reorganization proceeding. The Fund may obtain only a limited recovery or may obtain no recovery in such circumstances. In the event of a counterparty’s (or its affiliate’s) insolvency, the possibility exists that a Fund’s ability to exercise remedies, such as the termination of transactions, netting of obligations, and realization on collateral, could be stayed or eliminated under special resolution regimes adopted in the United States, the European Union, the United Kingdom, and various other jurisdictions. Among other things, such regimes provide government authorities with broad authority to intervene when a financial institution is experiencing financial difficulty.

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Currency Risk 

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Because foreign securities normally are denominated and traded in foreign currencies, the value of a Fund’s assets may be affected favorably or unfavorably by changes in currency exchange rates, currency exchange control regulations, intervention (or failure to intervene) by the U.S. or foreign governments

in currency markets, foreign withholding taxes, and restrictions or prohibitions on the repatriation of foreign currencies. A Fund may, but will not necessarily, engage in foreign currency transactions in order to protect against fluctuations in the values of holdings denominated in or exposed to other currencies, or, for certain Funds, to generate additional returns. Derivatives transactions providing exposure to foreign currencies may create investment leverage. A Fund’s investment in foreign currencies may increase the amount of ordinary income recognized by the Fund.

Officials in foreign countries may from time to time take actions in respect of their currencies which could significantly affect the value of a Fund’s assets denominated in those currencies or the liquidity of such investments. For example, a foreign government may unilaterally devalue its currency against other currencies, which would typically have the effect of reducing the U.S. dollar value of investments denominated in that currency. A foreign government may also limit the convertibility or repatriation of its currency or assets denominated in its currency, which would adversely affect the U.S. dollar value and liquidity of investments denominated in that currency. In addition, although at times most of a Fund’s income may be received or realized in foreign currencies, the Fund will be required to compute and distribute its income in U.S. dollars. As a result, if the exchange rate for any such currency declines after the Fund’s income has been earned and translated into U.S. dollars but before payment to shareholders, the Fund could be required to sell portfolio investments to make such distributions. Similarly, if a Fund incurs an expense in a foreign currency and the exchange rate changes adversely to the Fund before the expense is paid, the Fund would have to convert a greater amount of U.S. dollars to pay for the expense at that time than it would have had to convert at the time the Fund incurred the expense. Investments in foreign currencies themselves (directly or through derivatives transactions) may be highly volatile and may create investment leverage.

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Cyber Security and Technology Risk 

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The Funds and their service providers (including the Funds’ investment adviser, subadvisers, custodian, and transfer agent) are

subject to operational and information security risks, including those resulting from cyber-attacks and other technological issues. Technological issues or failures, or interference or attacks by “hackers” or others, may have the effect of disabling or hindering the Funds’ operations or the operations of a service provider to the Funds. There are inherent limitations in business continuity plans and technology systems designed to prevent cyber-attacks and avoid operational incidents, including the possibility that certain risks have not been identified. The Funds’ investment adviser does not control the cyber security plans and systems put in place by third-party service providers, and such third-party service providers may have limited indemnification obligations to the Funds’ investment adviser or the Funds, each of whom could be negatively impacted as a result. Any problems relating to the performance and effectiveness of security procedures used by a Fund or its service providers to protect a Fund’s assets, such as algorithms, codes, passwords, multiple signature systems, encryption, and telephone call-backs, may have an adverse impact on an investment in a Fund. Similar risks also are present for issuers of securities in which the Funds invest, which could result in material adverse consequences for such issuers, and may cause a Fund’s investment in such securities to lose value. Cyber security incidents and cyber-attacks (including denial of service attacks, ransomware attacks, and social engineering attempts (such as business email compromise attacks)) have been occurring globally at a more frequent and severe level and will likely continue to increase in frequency in the future (including as a consequence of the increased frequency of virtual working arrangements). Furthermore, there may be an increased risk of cyber-attacks during periods of geopolitical or military conflict, and geopolitical tensions may have increased the scale and sophistication of deliberate cyber-attacks, particularly those from nation-states or from entities with nation-state backing.

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Defaulted and Distressed Securities Risk 

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Defaulted securities risk refers to the uncertainty of repayment of defaulted securities and obligations of distressed issuers. Because the issuer of such securities is in default and is likely to be in distressed financial

condition, repayment of defaulted securities and obligations of distressed issuers (including insolvent issuers or issuers in payment or covenant default, in workout or restructuring, or in bankruptcy or insolvency proceedings) is subject to significant uncertainties. The market will likely be less liquid for distressed or defaulted securities than for other types of securities. Reduced liquidity can affect the valuations of distressed or defaulted securities, make their valuation and sale more difficult, and result in greater volatility. Insolvency laws and practices in foreign countries are different than those in the U.S. and the effect of these laws and practices cannot be predicted with certainty. Investments in defaulted securities and obligations of distressed issuers are considered speculative. To the extent a Fund is invested in distressed securities, its ability to achieve current income for its shareholders may be diminished.

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Derivatives Risk 

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Derivatives are financial contracts whose values depend upon, or are derived from, the value of an underlying asset, reference rate, or index. Derivatives may relate to stocks, bonds, interest rates, currencies, credit exposures, currency exchange rates, commodities, related indexes, or other assets. The use of derivative instruments may involve risks different from, or greater than, the risks associated with investing directly in securities and other more traditional investments. Derivatives can be highly volatile and are subject to a number of potential risks described in this Prospectus, including market risk, credit risk, management risk, liquidity risk, and leveraging risk. Derivative products are highly specialized instruments that may require investment techniques and risk analyses different from those associated with stocks and bonds. The use of a derivative requires an understanding not only of the underlying instrument or index but also of the derivative itself, often without the benefit of observing the performance of the derivative under all possible market conditions. (For example, successful use of a credit default swap may require, among other things, an understanding of both the credit of the company to which it relates and of the way the swap is likely to respond to changes in various market conditions and to factors specifically affecting

the company.) The use of derivatives involves the risk that a loss may be sustained as a result of the failure of another party to the contract (typically referred to as a “counterparty”) to make required payments or otherwise to comply with the contract’s terms. Derivative transactions can create investment leverage. Losses from derivatives can be substantially greater than the derivatives’ original cost and can sometimes be unlimited. Since the values of derivatives are calculated and derived from the values of other assets, reference rates, or indexes, there is greater risk that derivatives will be improperly valued. Derivatives also involve the risk that changes in the value of a derivative may not correlate perfectly with changes in the value of its underlying asset, rate, or index, and the risk that a derivative transaction may not have the effect or benefit the Fund’s investment adviser or subadviser anticipated. Also, suitable derivative transactions may not be available in all circumstances, and there can be no assurance that a Fund will engage in these transactions when that would be beneficial. A liquid secondary market may not always exist for a Fund’s derivative positions at any time. If a derivative transaction is particularly large or if the relevant market is illiquid (as is the case with many privately negotiated derivatives), it may not be possible to initiate a transaction or liquidate a position at an advantageous price or at all. Although the use of derivatives is intended to enhance a Fund’s performance, it may instead reduce returns and increase volatility.

U.S. and non-U.S. legislative and regulatory reforms, including those related to the Dodd-Frank Wall Street Reform and Consumer Protection Act, have resulted in, and may in the future result in, significant regulation of derivative instruments and the Funds’ use of such instruments. Such regulations can, among other things, restrict a Fund’s ability to engage in derivative transactions (for example, by making certain types of derivative instruments or transactions no longer available to a Fund), establish additional margin requirements and/or increase the costs of derivatives transactions, and a Fund may as a result be unable to execute its investment strategies in a manner its investment adviser or subadviser might

otherwise choose. Counterparty risk with respect to derivatives has been and may continue to be affected by rules and regulations concerning the derivatives market. Some derivatives transactions are centrally cleared, and a party to a cleared derivatives transaction is subject to the credit risk of the clearing house and the clearing member through which it holds the position. Credit risk of market participants with respect to derivatives that are centrally cleared is concentrated in a few clearing houses and clearing members, and it is not clear how an insolvency proceeding of a clearing house or clearing member would be conducted, what effect the insolvency proceeding would have on any recovery by a Fund, and what impact an insolvency of a clearing house or clearing member would have on the financial system more generally.

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Futures Contract Risk.  A Fund may enter into futures contracts, in which the Fund agrees to buy or sell certain financial instruments or index units or other assets on a specified future date at a specified price or rate. A Fund may also enter into contracts to deliver in the future an amount of one currency in return for an amount of another currency. If a Fund’s investment adviser or subadviser misjudges the direction of interest rates, markets, or foreign exchange rates, a Fund’s overall performance could suffer. The risk of loss could be far greater than the investment made because a futures contract requires only a small deposit to take a large position. A small change in a futures contract could have a substantial impact on a Fund, favorable or unfavorable. An investor could also suffer losses if it is unable to close out a futures contract because of an illiquid market. Futures are subject to the creditworthiness of the futures commission merchants or brokers and clearing organizations involved in the transactions. In the event of the insolvency of its futures commission merchant or broker, a Fund may be delayed or prevented from recovering some or all of the margin it has deposited with the merchant or broker, or any increase in the value of its futures positions held through that merchant or broker.

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Dollar Roll and Reverse Repurchase Agreement Transaction Risk 

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In a dollar roll transaction, a Fund sells mortgage-backed securities for delivery to the

buyer in the current month and simultaneously contracts to purchase similar securities on a specified future date from the same party. In a reverse repurchase agreement transaction, a Fund sells securities to a bank or securities dealer and agrees to repurchase them at an agreed time and price; a reverse repurchase agreement is similar to a secured borrowing by a Fund. Both types of transactions generally create leverage (see “Leveraging Risk” below). It may be difficult or impossible for a Fund to exercise its rights under a dollar roll transaction or reverse repurchase agreement in the event of the insolvency or bankruptcy of the counterparty, and the Fund may not be able to purchase the securities or other assets subject to the transaction and may be required to return any collateral it holds.

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Emerging Markets Risk 

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Investing in emerging market securities poses risks different from, and/or greater than, risks of investing in domestic securities or in the securities of foreign, developed countries. These risks may include, for example, smaller market-capitalizations of securities markets; significant price volatility; illiquidity; limits on foreign investment; and possible limits on repatriation of investment income and capital. Future economic or political events or crises could lead to price controls, forced mergers, expropriation or confiscatory taxation, seizure, nationalization, or the creation of government monopolies. The currencies of emerging market countries may experience significant declines against the U.S. dollar, and devaluation may occur subsequent to investments in those currencies by a Fund. Inflation and rapid fluctuations in inflation rates have had, and may continue to have, negative effects on the economies and securities markets of certain emerging market countries. Although many of the emerging market securities in which a Fund may invest are traded on securities exchanges, they may trade in limited volume, and the exchanges may not provide all of the conveniences or protections provided by securities exchanges in more developed markets.

Additional risks of emerging market securities may include greater social, economic, and political uncertainty and instability; more substantial governmental involvement in the economy; less governmental supervision and

regulation; greater custody and operational risks; unavailability of currency hedging techniques; less stringent investor protection and disclosure standards; less reliable settlement practices; companies that are newly organized and small; differences in auditing and financial reporting standards, which may result in unavailability or unreliability of material information about issuers or instruments; less developed legal, regulatory, and accounting systems; and greater environmental risk. Many emerging market countries are highly reliant on international trade and exports, including the export of commodities. Their economies may be significantly impacted by fluctuations in commodity prices and the global demand for certain commodities. In addition, pandemics and outbreaks of contagious diseases may exacerbate pre-existing problems in emerging market countries with less established health care systems. In addition, emerging securities markets may have different clearance and settlement procedures, which may be unable to keep pace with the volume of securities transactions or otherwise make it difficult to engage in such transactions. Settlement of securities transactions in emerging markets may be subject to risk of loss and may be delayed more often than transactions settled in the United States, in part because a Fund will need to use brokers and counterparties that are less well capitalized, and custody and registration of assets in some countries may be unreliable compared to more developed countries. Settlement problems may cause a Fund to miss attractive investment opportunities, hold a portion of its assets in cash pending settlement, or be delayed in disposing of a portfolio security. It may be more difficult to obtain and/or enforce a judgment in a court outside the U.S., and a judgment against a foreign government may be unenforceable.

Frontier markets, a subset of emerging markets, generally have smaller economies and less mature capital markets than emerging markets. As a result, the risks of investing in emerging market countries are magnified in frontier market countries. Frontier markets are more susceptible to having abrupt changes

in currency values, less mature markets and settlement practices, and lower trading volumes that could lead to greater price volatility and illiquidity.

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Equity Securities Risk 

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Although stocks may have the potential to outperform other asset classes over the long term, their prices tend to fluctuate more dramatically over the shorter term. These movements may result from factors affecting individual companies, or from broader influences like changes in interest rates, market conditions, or investor confidence, or announcements of economic, political, or financial information.

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Fixed Income Securities Risk 

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The values of debt securities change in response to interest rate changes. In general, as interest rates rise, the value of a debt security is likely to fall. This risk is generally greater for obligations with longer maturities or for debt securities that do not pay current interest (such as zero-coupon securities). Debt securities with variable and floating interest rates can be less sensitive to interest rate changes, although, to the extent a Fund’s income is based on short-term interest rates that fluctuate over short periods of time, income received by the Fund may decrease as a result of a decline in interest rates. The value of a debt security also depends on the issuer’s actual or perceived credit quality or ability to pay principal and interest when due. The value of a debt security is likely to fall if an issuer or the guarantor of a security is unable or unwilling (or is perceived to be unable or unwilling) to make timely principal and/or interest payments or otherwise to honor its obligations or if the debt security’s rating is downgraded by a credit rating agency. The value of a debt security can also decline in response to changes in market, economic, industry, political, regulatory, public health, and other conditions that affect a particular type of debt security or issuer or debt securities generally. Certain events, such as market or economic developments, regulatory or government actions, natural disasters, pandemics, terrorist attacks, war, and other

geopolitical events can have a dramatic adverse effect on the debt market and the overall liquidity of the market for fixed income securities.

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Extension Risk. During periods of rising interest rates, the average life of certain types of securities may be extended because of slower than expected principal payments. This may lock in a below-market interest rate, increase the security’s duration, and reduce the value of the security.

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Prepayment Risk. Prepayment risk is the risk that principal of a debt obligation will be repaid at a faster rate than anticipated. In such a case, a Fund may lose the benefit of a favorable interest rate for the remainder of the term of the security in question, and may only be able to reinvest the amount of the prepayment at a less favorable rate.

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Interest Rate Risk. The values of bonds and other debt instruments usually rise and fall in response to changes in interest rates. The values of debt instruments generally increase in response to declines in interest rates and decrease in response to rises in interest rates. Interest rates can also change in response to the supply and demand for credit, government and/or central bank monetary policy and action, inflation rates, and other factors. Interest rate risk is generally greater for fixed-rate instruments than floating-rate instruments and for investments with longer durations or maturities. Some investments give the issuer the option to call or redeem an investment before its maturity date. If an issuer calls or redeems an investment during a time of declining interest rates, a Fund might have to reinvest the proceeds in an investment offering a lower yield, and therefore might not benefit from any increase in value as a result of declining interest rates. Negative or very low interest rates could magnify the risks associated with changes in interest rates. In general, changing interest rates, including rates that fall below zero, could have unpredictable effects on markets and may expose fixed income and related markets to heightened levels of interest rate volatility and liquidity risk. Potential future changes in government and/or central bank monetary policy and action may also affect the level of interest rates. Monetary policy measures have in the past, and may in

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the future, exacerbate risks associated with rising interest rates.

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Foreign Investment Risk 

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Investments in securities of foreign issuers, securities of companies with significant foreign exposure, and foreign currencies can involve additional risks relating to market, industry, political, regulatory, public health, and other conditions. Political, social, diplomatic, and economic developments, U.S. and foreign government action, or threat thereof, such as the imposition of currency or capital blockages, controls, or tariffs, economic and trade sanctions or embargoes, security trading suspensions, entering or exiting trade or other intergovernmental agreements, or the expropriation or nationalization of assets in a particular country, can cause dramatic declines in certain or all securities with exposure to that country and other countries. Sanctions, or the threat of sanctions, may cause volatility in regional and global markets and may negatively impact the performance of various sectors and industries, as well as companies in other countries, which could have a negative effect on the performance of a Fund. Economic or other sanctions imposed on a foreign country or issuer by the U.S., or on the U.S. by a foreign country, could impair a Fund’s ability to buy, sell, hold, receive, deliver, or otherwise transact in certain securities. In the event of nationalization, expropriation, confiscation, or other government action, intervention, or restriction, a Fund could lose its entire investment in a particular foreign issuer or country. Civil unrest, geopolitical tensions, armed conflicts, wars, and acts of terrorism are other potential risks that could adversely affect an investment in a foreign security or in foreign markets or issuers generally. There may be quotas or other limits on the ability of a Fund (or clients of a Fund’s investment adviser or subadviser) to invest or maintain investments in securities of issuers in certain countries. Enforcing legal rights can be more difficult, costly, and limited in certain foreign countries and with respect to certain types of investments, and can be particularly difficult against foreign governments. Because non-U.S. securities are normally denominated and traded in currencies other than the U.S. dollar, the value of a Fund’s assets may be affected favorably or

unfavorably by changes in currency exchange rates, exchange control regulations, and restrictions or prohibitions on the repatriation of non-U.S. currencies.

Income and gains with respect to investments in certain countries may be subject to withholding and other taxes. There may be less information publicly available about a non-U.S. company than about a U.S. company, and many non-U.S. companies are not subject to accounting, auditing, and financial reporting standards, regulatory framework and practices comparable to those in the United States. The securities of some non-U.S. companies are less liquid and at times more volatile than securities of comparable U.S. companies. Non-U.S. transaction costs, such as brokerage commissions and custody costs may be higher than in the United States. In addition, foreign markets can perform differently from U.S. markets and can react differently to market, economic, industry, political, regulatory, geopolitical, public health, and other conditions than the U.S. market.

The willingness and ability of foreign governmental entities to pay principal and interest on government securities depends on various economic factors, including for example the issuer’s balance of payments, overall debt level, and cash-flow considerations related to the availability of tax or other revenues to satisfy the issuer’s obligations. If a foreign governmental entity defaults on its obligations on the securities, a Fund may have limited recourse available to it. The laws of some foreign countries may limit a Fund’s ability to invest in securities of certain issuers located in those countries. Special tax considerations apply to a Fund’s investments in foreign securities. A Fund’s investments in foreign securities or foreign currencies may increase or accelerate the Fund’s recognition of ordinary income and may affect the amount, timing, or character of the Fund’s distributions.

A Fund may invest in foreign securities known as depositary receipts, in the form of American Depositary Receipts (“ADRs”), European Depositary Receipts (“EDRs”), Global Depositary Receipts (“GDRs”), or other similar securities. An ADR is a U.S. dollar-denominated security issued by a U.S. bank or trust company that represents, and may be

converted into, a foreign security. An EDR or a GDR is generally similar but is issued by a non-U.S. bank. Depositary receipts are subject to the same risks as direct investment in foreign securities. Depositary receipts may not necessarily be denominated in the same currency as the underlying securities into which they may be converted, and changes in currency exchange rates may affect the value of an ADR investment in ways different from direct investments in foreign securities. Funds may invest in both sponsored and unsponsored depositary receipts. Unsponsored depositary receipts are organized independently and without the cooperation of the issuer of the underlying securities. As a result, available information concerning the issuers may not be as current for unsponsored depositary receipts and the prices of unsponsored depositary receipts may be more volatile than if such instruments were sponsored by the issuer. In addition, the underlying issuers of certain depositary receipts, particularly unsponsored or unregistered depositary receipts, are under no obligation to distribute shareholder communications to the holders of such receipts or to pass through to them any voting rights with respect to the deposited securities. A Fund may therefore receive less timely information or have less control than if it invested directly in the foreign issuer. An investment in an ADR is subject to the credit risk of the issuer of the ADR.

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Frequent Trading/Portfolio Turnover Risk 

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The length of time a Fund has held a particular security is not generally a consideration in investment decisions. The investment policies of a Fund may lead to frequent changes in the Fund’s investments, particularly in periods of volatile market movements, in order to take advantage of what the Fund’s investment adviser or subadviser believes to be temporary investment opportunities. A change in the securities held by a Fund is known as “portfolio turnover.” Portfolio turnover generally involves some expense to a Fund, including brokerage commissions, bid-asked spreads, dealer mark-ups, and other transaction costs on the sale of securities and reinvestments in other securities. The trading costs associated with portfolio turnover may adversely affect a Fund’s performance.

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Geographic Focus Risk 

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When a Fund invests a relatively large percentage of its assets in issuers located in a single country, a small number of countries, or a particular geographic region, the Fund’s performance could be closely tied to the market, currency, economic, political, or regulatory conditions and developments in those countries or that region, and could be more volatile than the performance of more geographically diversified funds.

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Growth Company Risk 

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Growth company securities tend to be more volatile in terms of price swings and trading volume than many other types of equity securities. Growth companies, especially technology related companies, have seen dramatic rises and falls in stock valuations. Funds that invest in growth companies are subject to the risk that the market may deem these companies’ stock prices over-valued, which could cause steep and/or volatile price swings. Also, since investors buy these stocks because of their expected superior earnings growth, earnings disappointments often result in sharp price declines.

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Hedging Risk 

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There can be no assurance that a Fund’s hedging transactions will be effective. If a Fund takes a short position in a particular currency, security, or bond market, it will lose money if the currency, security, or bond market appreciates in value, or an expected credit event fails to occur. Any efforts at buying or selling currencies could result in significant losses for the Fund. Further, foreign currency transactions that are intended to hedge the currency risk associated with investing in foreign securities and minimize the risk of loss that would result from a decline in the value of the hedged currency may also limit any potential gain that might result should the value of such currency increase.

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Index Funds Risk 

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Certain ETFs may attempt to track the performance of a specified index. Therefore, securities may be purchased, retained, and sold by the ETF at times when an actively managed fund would not do so. The structure and composition of the index will affect the performance, volatility, and risk of the index

and, consequently, the performance, volatility, and risk of the ETF. While the investment adviser or subadviser seeks to track the performance of the index (i.e., achieve a high degree of correlation with the index), the ETF’s return may not match the return of the index. The ETF incurs a number of operating expenses not applicable to the index, and may incur costs in buying and selling securities. In addition, the ETF may not be fully invested at times, generally as a result of cash flows into or out of the ETF.

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Inflation Risk 

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The value of assets or income from a Fund’s investments will be less in the future as inflation decreases the value of money. As inflation increases, the value of a Fund’s assets can decline as can the value of the Fund’s distributions. Inflation rates may change frequently and drastically as a result of various factors, including unexpected shifts in the domestic or global economy (or expectations that such policies will change), and a Fund’s investments may not keep pace with inflation, which may result in losses to the Fund’s investors. The market prices of debt securities generally fall as inflation increases because the purchasing power of the future income and repaid principal is expected to be worth less when received by the Fund. Debt securities that pay a fixed rather than variable interest rate are especially vulnerable to inflation risk because variable-rate debt securities may be able to participate, over the long term, in rising interest rates which have historically accompanied long-term inflationary trends.

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Inflation-Linked Securities Risk 

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Inflation-linked securities are typically fixed income securities whose principal values are periodically adjusted according to a measure of inflation. Inflation rates may change frequently and drastically as a result of various factors, including unexpected shifts in the domestic or global economy (or expectations that such policies will change), and a Fund’s investments may not keep pace with inflation, which may result in losses to the Fund’s investors. If the index measuring inflation falls, the principal value of an inflation-linked security will be adjusted downward, and consequently the interest payable on the security (calculated with respect to a smaller principal amount) will

be reduced. Repayment of the original principal of the security upon maturity (as adjusted for inflation) is guaranteed in the case of U.S. Treasury inflation-linked securities. For securities that do not provide a similar guarantee, the adjusted principal value of the security repaid at maturity may be less than the original principal.

Alternatively, the interest rates payable on certain inflation-linked securities may be adjusted according to a measure of inflation. As a result, the principal values of such securities do not adjust according to the rate of inflation, although the interest payable on such securities may decline during times of falling inflation.

The values of inflation-linked securities are expected to change in response to changes in real interest rates. Real interest rates are tied to the relationship between nominal interest rates and the rate of inflation. If nominal interest rates increase at a faster rate than inflation, real interest rates may rise, leading to a decrease in value of inflation-linked securities. Inflation-linked securities may cause a potential cash flow mismatch to investors, because an increase in the principal amount of an inflation-linked security will be treated as interest income even though investors will not receive repayment of principal until maturity. If a Fund invests in such securities, it will be required to distribute such interest income in order to qualify for treatment as a regulated investment company and eliminate the Fund-level tax, without a corresponding receipt of cash, and therefore may be required to dispose of portfolio securities at a time when it may not be advantageous to do so in order to make such distributions.

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Large Company Risk 

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Large-capitalization stocks as a group could fall out of favor with the market, causing a Fund’s investments in large-capitalization stocks to underperform investments that focus on small- or medium-capitalization stocks. Larger, more established companies may be slow to respond to challenges, including changes to technology or consumer tastes, and may grow more slowly than smaller companies, especially during market cycles corresponding

to periods of economic expansion. Market capitalizations of companies change over time.

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Leveraging Risk 

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The use of leverage has the potential to increase returns to shareholders, but also involves additional risks. A Fund may create leverage by borrowing money (through traditional borrowings or by means of so-called reverse repurchase agreements); certain transactions, including, for example, when-issued, delayed-delivery, to-be-announced, and forward commitment purchases, loans of portfolio securities, dollar roll transactions, and the use of some derivatives, can also result in leverage. Leverage will increase the volatility of the Fund’s investment portfolio and could result in larger losses than if it were not used. The use of leverage is considered to be a speculative investment practice and may result in losses to a Fund. Certain derivatives have the potential for unlimited loss, regardless of the size of the initial investment. A Fund will typically pay interest or incur other borrowing costs in connection with leverage transactions.

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Liquidity Risk 

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Liquidity risk is the risk that particular investments may be difficult to sell or terminate at approximately the price at which the Fund is carrying the investments. The ability of a Fund to dispose of illiquid positions at advantageous prices may be greatly limited, and a Fund may have to continue to hold such positions during periods when the investment adviser or subadviser otherwise would have sold them. Some securities held by a Fund may be restricted as to resale, may trade in the over-the-counter (“OTC”) market, or may not have an active trading market due to adverse market, economic, industry, political, regulatory, geopolitical, public health, or other conditions, including trading halts, sanctions, or wars. In addition, a Fund, by itself or together with other accounts managed by the investment adviser or subadviser, may hold a position in a security that is large relative to the typical trading volume for that security, which can make it difficult for the Fund to dispose of the position at an advantageous time or price.

Market values for illiquid securities may not be readily available, and there can be no assurance that any fair value assigned to an illiquid security at any time will accurately reflect the price a Fund might receive upon the sale of that security. It is possible that, during periods of extreme market volatility or unusually high and unanticipated levels of redemptions or in the case of a liquidation of a Fund, a Fund may be forced to sell large amounts of securities or terminate outstanding transactions at a price or time that is not advantageous in order to meet redemptions or other cash needs or to pay liquidation proceeds. In such a case, the sale proceeds received by a Fund may be substantially less than if the Fund had been able to sell the securities or terminate the transactions in more orderly transactions, and the sale price may be substantially lower than the price previously used by the Fund to value the securities for purposes of determining the Fund’s NAV. To the extent a Fund holds illiquid securities, it may be more likely to pay redemption proceeds in kind.

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Management and Operational Risk 

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Each Fund is subject to management risk because it relies on the investment adviser’s and/or subadviser’s investment analysis and its selection of investments to achieve its investment objective, and each Fund is subject to the risk that the manager’s assessment of an investment is wrong. A Fund’s investment adviser or subadviser manages the Fund based on its assessment of economic, financial, and market factors and its investment judgment. The investment adviser or subadviser may fail to ascertain properly the appropriate mix of securities for any particular economic cycle. A Fund’s investment adviser or subadviser applies its investment techniques and risk analyses in making investment decisions for the Fund, but there can be no guarantee that they will produce the intended result. Management risk includes the risk that poor security selection will cause a Fund to underperform relative to other funds with similar investment objectives, or that the timing of movements from one type of security to another could have a negative effect on the overall investment performance of the Fund. There can be no assurance that there will be a liquid market for instruments held by the

Fund at any time. The Funds are also subject to operational risks resulting from other services provided by a Fund’s investment adviser, subadviser, and other service providers, including pricing, administrative, accounting, tax, legal, custody, transfer agency, and other operational services. Examples of such operational risks include the possibility of loss caused by inadequate procedures and controls, human error, and system failures by a service provider. For example, trading delays or errors could prevent a Fund from benefiting from investment gains or avoiding losses. In addition, a service provider may be unable to provide an NAV for a Fund or share class on a timely basis. Additionally, legislative, regulatory, or tax developments may adversely affect management of a Fund and, therefore, the ability of the Fund to achieve its investment objective.

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Market Risk 

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The values of a Fund’s portfolio securities may decline, at times sharply and unpredictably, as a result of unfavorable broad market developments, which may affect securities markets generally or particular industries, sectors, or issuers. The values of a Fund’s investments may decline as a result of a number of such factors, including actual or perceived changes in general economic and market conditions, industry, political, regulatory, geopolitical, public health, and other developments, including U.S. presidential elections, the imposition of tariffs or other protectionist actions, changes in interest rates, currency rates, or other rates of exchange, and changes in economic and competitive industry conditions. Likewise, terrorism, war, natural and environmental disasters, and epidemics or pandemics may be highly disruptive to economies and markets. For example, the global pandemic outbreak of the novel coronavirus known as COVID-19 and efforts to contain its spread produced substantial market volatility, severe market dislocations and liquidity constraints in many markets, exchange trading suspensions and closures, higher default rates, and global business disruption, and they may result in future significant adverse effects. Such factors, and the effects of other infectious illness outbreaks, epidemics, or pandemics, may have a significant adverse effect on a Fund’s

performance and have the potential to impair the ability of a Fund’s investment adviser, subadviser, or other service providers to serve the Fund and could lead to disruptions that negatively impact the Fund. Different parts of the market and different types of securities can react differently to these conditions. The possibility that security prices in general will decline over short or even extended periods subjects a Fund to unpredictable declines in the value of its shares, as well as potentially extended periods of poor performance. In addition, the increasing popularity of passive index-based investing may have the potential to increase security price correlations and volatility. As passive strategies generally buy or sell securities based simply on inclusion and representation in an index, securities’ prices will have an increasing tendency to rise or fall based on whether money is flowing into or out of passive strategies rather than based on an analysis of the prospects and valuation of individual securities. This may result in increased market volatility as more money is invested through passive strategies.

Federal, state, and other governments, their regulatory agencies, or self-regulatory organizations may take actions that affect the regulation of the securities in which a Fund invests or the issuers of such securities in ways that are unforeseeable. The uncertainty surrounding the sovereign debt of a significant number of European Union countries, as well as the status of the Euro, the European Monetary Union, and the European Union itself, has disrupted and may continue to disrupt markets in the U.S. and around the world. The risks associated with investments in Europe may be heightened due to the United Kingdom’s exit from the European Union on January 31, 2020. An agreement between the United Kingdom and the European Union governing their future trade relationship became effective on January 1, 2021. The full extent of the political, economic, and legal consequences of Brexit are not yet fully known, and the long-term impact of Brexit on the United Kingdom, the European Union, and the broader global economy may be significant. The range and potential implications of possible political, regulatory, economic, and market outcomes are difficult to predict. There is the potential for decreased trade, capital outflows from the United

Kingdom, devaluation of the pound sterling, decreased business and consumer spending and decreased foreign investment in the United Kingdom, and negative effects on the value of a Fund’s investments and/or on a Fund’s ability to enter into certain transactions or value certain investments. Any further exits from the European Union, the possibility of such exits, the partial or complete dissolution of the European Union, or the abandonment of the Euro may cause additional market disruption globally, adversely affect the world’s economies and securities markets, and introduce new legal and regulatory uncertainties. Legislation or regulation also may change the way in which a Fund, the investment adviser, or subadviser is regulated. Such legislation, regulation, or other government action could limit or preclude a Fund’s ability to achieve its investment objective and affect the Fund’s performance.

In addition, military action by Russia in Ukraine could adversely affect global energy and financial markets, including through global supply chain disruptions, increased inflationary pressures, and reduced economic activity, and therefore could affect the value of a Fund’s investments, including beyond the Fund’s direct exposure to Russian issuers or nearby geographic regions. The extent and duration of the military action, sanctions, or the threat of sanctions (including any Russian retaliatory responses to such sanctions), and resulting market disruptions are impossible to predict and could be substantial. Other issuers or markets could be similarly affected by past or future geopolitical or other events or conditions.

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Money Market Instruments Risk 

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The value of a money market instrument typically will decline during periods of rising interest rates, and can also decline in response to changes in the financial condition of the issuer, borrower, counterparty, or underlying collateral assets, or changes in market, economic, industry, political, regulatory, public health, and other conditions affecting a particular type of security or issuer or fixed income securities generally. Certain events, such as changes in the financial condition of the issuer or borrower, specific market or economic developments, regulatory or government actions, natural disasters,

pandemics, terrorist attacks, war, and other geopolitical events can have a dramatic adverse effect on the debt market and the overall liquidity of the market for money market instruments. On July 12, 2023, the Securities and Exchange Commission adopted amendments to money market fund regulation that will, once effective, increase the daily and weekly liquid asset minimum requirements for the Fund, among other changes. The Fund’s operations will be impacted as it comes into compliance with the new regulations.

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Mortgage- and Asset-Backed Securities Risk 

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Investments in mortgage-related and other asset-backed securities are subject to the risk of severe credit downgrades, illiquidity and defaults to a greater extent than many other types of fixed income investments. Mortgage-backed securities, including collateralized mortgage obligations and certain stripped mortgage-backed securities, represent a participation in, or are secured by, mortgage loans. Asset-backed securities are generally structured like mortgage-backed securities, but instead of mortgage loans or interests in mortgage loans, the underlying assets may include such items as motor vehicle installment sale or installment loan contracts, leases of various types of real and personal property, receivables from credit card agreements, and student loan payments. Asset-backed securities also may be backed by pools of corporate or sovereign bonds, loans made to corporations, or a combination of these bonds and loans, commonly referred to as “collateralized debt obligations,” including collateralized bond obligations (“CBOs”) and collateralized loan obligations (“CLOs”). The assets backing collateralized debt obligations may consist in part or entirely of high risk, below investment grade debt obligations (or comparable unrated obligations). In the case of CBOs and certain other collateralized debt obligations, those may include, by way of example, high yield debt, residential privately issued mortgage-related securities, commercial privately issued mortgage-related securities, trust preferred securities, and emerging market debt. In the case of CLOs, they may include, among other things, domestic and foreign senior secured loans, senior unsecured loans, and subordinate corporate loans, any or all of which may be

rated below investment grade or may be comparable unrated obligations.

Traditional debt investments typically pay a fixed rate of interest until maturity, when the entire principal amount is due. By contrast, payments on mortgage-backed and many asset-backed investments typically include both interest and partial payment of principal. Principal may also be prepaid voluntarily, or as a result of refinancing or foreclosure. The Fund may have to invest the proceeds from prepaid investments in other investments with less attractive terms and yields. As a result, these securities may have less potential for capital appreciation during periods of declining interest rates than other securities of comparable maturities, although they may have a similar risk of decline in market value during periods of rising interest rates. Because the prepayment rate generally declines as interest rates rise, an increase in interest rates will likely increase the duration, and thus the volatility, of mortgage-backed and asset-backed securities. (Duration is a measure of the expected life of a fixed income security that is used to determine the sensitivity of the security’s price to changes in interest rates. Unlike the maturity of a fixed income security, which measures only the time until final payment is due, duration takes into account the time until all payments of interest and principal on a security are expected to be made, including how these payments are affected by prepayments and by changes in interest rates.) Prepayment rates are difficult to predict and the potential impact of prepayments on the value of a mortgage-related or other asset-backed security depends on the terms of the instrument and can result in significant volatility. In addition to interest rate risk (as described under “Interest Rate Risk”), investments in mortgage-backed securities composed of subprime mortgages and investments in CDOs and CLOs backed by pools of high-risk, below investment grade debt securities may be subject to a higher degree of credit risk, valuation risk, and liquidity risk (as described under “Credit Risk,” “Valuation Risk,” and “Liquidity Risk”). During periods of deteriorating economic conditions, such as recessions or periods of rising unemployment, delinquencies

and losses generally increase, sometimes dramatically, with respect to securitizations involving loans, sales contracts, receivables, and other obligations underlying mortgage-related and other asset-backed securities. Litigation with respect to the representations and warranties given in connection with the issuance of mortgage-backed securities can be an important consideration in investing in such securities, and the outcome of any such litigation could significantly impact the value of the Fund’s mortgage-backed investments.

The types of mortgages underlying securities held by the Fund may differ and may be affected differently by market factors. For example, the Fund’s investments in residential mortgage-backed securities will likely be affected significantly by factors affecting residential real estate markets and mortgages generally; similarly, investments in commercial mortgage-backed securities will likely be affected significantly by factors affecting commercial real estate markets and mortgages generally. Furthermore, a Fund’s investments in mortgage-backed securities may make the Fund’s NAV more susceptible to economic, market, political, and other developments affecting the residential and commercial real estate markets and the servicing of mortgage loans secured by real estate properties. During periods of difficult economic conditions, delinquencies and losses on commercial mortgage-backed investments in particular generally increase, including as a result of the effects of those conditions on commercial real estate markets, the ability of commercial tenants to make loan payments, and the ability of a property to attract and retain commercial tenants. Additionally, certain types of real estate may be adversely affected by changing usage trends, such as office buildings as a result of work-from-home practices and commercial facilities as a result of an increase in online shopping, which could in turn result in defaults and declines in value of mortgage-backed securities secured by such properties.

Some mortgage-backed and asset-backed investments receive only the interest portion (“IOs”) or the principal portion (“POs”) of

payments on the underlying assets. The yields and values of these investments are extremely sensitive to changes in interest rates and in the rate of principal payments on the underlying assets. IOs tend to decrease in value if interest rates decline and rates of repayment (including prepayment) on the underlying mortgages or assets increase; it is possible that the Fund may lose the entire amount of its investment in an IO due to a decrease in interest rates. Conversely, POs tend to decrease in value if interest rates rise and rates of repayment decrease. Moreover, the market for IOs and POs may be volatile and limited, which may make them difficult for the Fund to buy or sell. The values of mortgage-related and other asset-backed securities may be substantially dependent on the servicing of the underlying asset pools, and are therefore subject to risks associated with the negligence or malfeasance by their servicers and to the credit risk of their servicers. In certain situations, the mishandling of related documentation may also affect the rights of securities holders in and to the benefits of the underlying collateral. There may be legal and practical limitations on the enforceability of any security interest granted with respect to underlying assets, or the value of the underlying assets, if any, may be insufficient if the issuer defaults.

The Fund may gain investment exposure to mortgage-backed and asset-backed investments by entering into agreements with financial institutions to buy the investments at a fixed price at a future date. The Fund may or may not take delivery of the investments at the termination date of such an agreement, but will nonetheless be exposed to changes in value of the underlying investments during the term of the agreement. These transactions may create investment leverage.

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Non-Diversification Risk 

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A “non-diversified” mutual fund may purchase larger positions in a smaller number of issuers than may a diversified mutual fund. Therefore, an increase or decrease in the value of the securities of a single issuer or a small number of issuers may have a greater impact on the

Fund’s NAV and the Fund’s performance could be more volatile than the performance of diversified funds.

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Preferred Stock Risk 

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Like other equity securities, preferred stock is subject to the risk that its value may decrease based on actual or perceived changes in the business or financial condition of the issuer. In addition, if interest rates rise, the dividends on preferred stocks may be less attractive, causing the prices of preferred stocks to decline. Preferred stock may have mandatory sinking fund provisions or call/redemption provisions that can negatively affect its value. In addition, in the event of liquidation of a corporation’s assets, the rights of preferred stock generally are subordinate to the rights associated with a corporation’s debt securities. Preferred stocks are also subject to additional risks, such as potentially greater volatility and risks related to deferral, non-cumulative dividends, subordination, liquidity, limited voting rights, and special redemption rights.

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Quantitative Models Risk  

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Certain portfolio managers use quantitative models as part of the idea generation process. Quantitative models are based upon many factors that measure individual securities relative to each other. Such models may not produce the intended results and can be adversely affected by errors or imperfections in the factors or the data on which measurements are based, changing sources of market return or market risk, human error, or any technical issues with or errors in the design, construction, implementation, or maintenance of the models.

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Real Estate Risk; REIT Risk 

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Investments in real estate are subject to a number of risks, including losses from casualty, condemnation or natural disasters, and changes in local and general economic conditions, supply and demand, interest rates, zoning laws, environmental regulations and other governmental action, regulatory limitations on rents, property taxes, and operating expenses. The U.S. residential and commercial real estate markets may, in the future, experience and have, in the past, experienced a decline in value, with certain regions experiencing significant losses in

property values. When growth is slowing, demand for property decreases and prices may decline, which could impact the value of real estate investments as well as mortgage-backed securities that may be held by a Fund. Although interest rates have significantly increased in recent years, the prices of real estate-related assets generally have not decreased as much as may be expected based on historical correlations between interest rates and prices of real estate-related assets. This presents an increased risk of a correction or severe downturn in real estate-related asset prices, which could adversely impact the value of other investments as well (such as loans, securitized debt, and other fixed income securities). This risk is particularly present with respect to commercial real estate-related asset prices, and the value of other investments with a connection to the commercial real estate sector. Exposure to such real estate may adversely affect Fund performance. An investment in a REIT may be subject to risks similar to those associated with direct ownership of real estate, and may be subject to additional risks, such as poor performance by the manager of the REIT, adverse changes to the tax laws or failure by the REIT to qualify for favorable tax treatment under the Internal Revenue Code of 1986, as amended (the “Code”), and to the risk of general declines in stock prices. In addition, some REITs have limited diversification because they invest in a limited number of properties, a narrow geographic area, or a single type of property. A “mortgage” REIT that invests most or all of its assets in mortgages will be subject to many of the risks described above in respect of mortgage-backed securities. Also, the organizational documents of a REIT may contain provisions that make changes in control of the REIT difficult and time-consuming. As a shareholder in a REIT a Fund, and indirectly the Fund’s shareholders, would bear its ratable share of the REIT’s expenses and would at the same time continue to pay its own fees and expenses. Real estate-related investments may entail leverage and may be highly volatile. The securities of small real-estate issuers can be more volatile and less liquid than securities of larger issuers and their issuers can have more limited financial resources.

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Redemptions by Affiliated Funds and by Other Significant Investors 

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A Fund may be an investment option for other MassMutual Funds that are managed as “funds of funds” and for other investors who may make substantial investments in the Fund. As a result, from time to time, a Fund may experience a relatively large redemption and could be required to liquidate assets at inopportune times or at a loss or depressed value, which could cause the value of your investment to decline. Similarly, large Fund share purchases may adversely affect a Fund’s performance to the extent that the Fund is delayed in investing new cash and is required to maintain a larger cash position than it ordinarily would, or if the Fund is unable to invest the cash in portfolio securities that it considers as desirable as the Fund’s portfolio securities.

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Reinvestment Risk 

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Income from a Fund’s portfolio will decline if and when the Fund invests the proceeds from matured, traded, or called debt obligations at market interest rates that are below the portfolio’s current earnings rate. A decline in income could affect a Fund’s overall return.

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Repurchase Agreement Risk 

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A Fund may enter into repurchase agreements. These transactions must be fully collateralized, but involve credit risk to a Fund if the other party should default on its obligation and the Fund is delayed or prevented from recovering the collateral, or if the Fund is required to return collateral to a borrower at a time when it may realize a loss on the investment of that collateral.

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Restricted Securities Risk 

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A Fund may hold securities that are restricted as to resale under the U.S. federal securities laws, such as securities in certain privately held companies. There can be no assurance that a trading market will exist at any time for any particular restricted security. Limitations on the resale of these securities may prevent the Fund from disposing of them promptly at reasonable prices or at all. Restricted securities may be highly illiquid. A Fund may have to bear the expense of registering the securities for resale and the risk of substantial delays in effecting the registration. Restricted securities

may be difficult to value because market quotations may not be readily available, and there may be little publicly available information about the securities or their issuers. The values of restricted securities may be highly volatile.

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Risk of Investment in other Funds or Pools 

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A Fund may invest in other investment companies or pooled vehicles, including closed-end funds, trusts, and ETFs, that are advised by the Fund’s investment adviser or subadviser, as applicable, their affiliates, or by unaffiliated parties, to the extent permitted by applicable law. As a shareholder in an investment company or other pool, the Fund, and indirectly that Fund’s shareholders, bear a ratable share of the investment company’s or pool’s expenses, including, but not limited to, advisory and administrative fees, and the Fund at the same time continues to pay its own fees and expenses. Investment companies or pools in which the Funds may invest may change their investment objectives or policies without the approval of a Fund, in which case a Fund may be forced to withdraw its investment from the investment company or pool at a disadvantageous time. Private investment pools in which the Funds may invest are not registered under the 1940 Act, and so will not offer all of the protections provided by the 1940 Act (including, among other things, independent oversight, protections against certain conflicts of interest, and custodial risks). A Fund is exposed indirectly to all of the risks applicable to any other investment company or pool in which it invests, including that the investment company or pool will not perform as expected. Investments in other investment companies or private pools may be illiquid, may be leveraged, and may be highly volatile.

Investing in other investment companies or private investment vehicles sponsored or managed by the investment adviser or subadviser, as applicable, or affiliates of the investment adviser or subadviser, as applicable, involves potential conflicts of interest. For example, the investment adviser or subadviser, as applicable, or their affiliates may receive fees based on the amount of assets invested in such other investment vehicles, which fees may be higher than the fees the investment

adviser or subadviser, as applicable, receives for managing the investing Fund. Investment by a Fund in those other vehicles may be beneficial in the management of those other vehicles, by helping to achieve economies of scale or enhancing cash flows. Due to this and other factors, the investment adviser or subadviser, as applicable, will have an incentive to invest a portion of a Fund’s assets in investment vehicles sponsored or managed by the investment adviser or subadviser, as applicable, or their affiliates in lieu of investments by the Fund directly in portfolio securities, and will have an incentive to invest in such investment vehicles over non-affiliated investment companies. The investment adviser or subadviser, as applicable, will have no obligation to select the least expensive or best performing funds available to serve as an underlying investment vehicle. Similarly, the investment adviser or subadviser, as applicable, will have an incentive to delay or decide against the sale of interests held by the Fund in investment vehicles sponsored or managed by the investment adviser or subadviser, as applicable, or their affiliates.

ETFs are subject to many of the same risks applicable to investments in mutual funds generally, including that an ETF will not perform as anticipated, that a Fund will bear its proportionate share of the ETF’s fees and expenses, and that the ETF will lose money. ETFs are also subject to additional risks, including, among others, the risk that the market price of an ETF’s shares may trade above or below its NAV, the risk that an active trading market for an ETF’s shares may not develop or be maintained, the risk that trading of an ETF’s shares may be halted, and the risk that the ETF’s shares may be delisted from the listing exchange. A Fund will generally purchase and sell shares of ETFs in the secondary market and will be subject to these secondary market trading risks. Some ETFs engage in derivatives strategies and use leverage, and as a result their values can be highly volatile. It is possible that an ETF’s performance will diverge from the performance of any index or indexes it seeks to replicate. Because shares of ETFs may be actively traded, their values may be affected in unanticipated ways by the effects of supply and demand in the market for shares of ETFs, activities of short sellers, or unusual speculative

activity in their shares. Some ETFs may experience periods of reduced liquidity due to restrictions on trading activity or due to a general lack of investor interest in the asset class represented by the ETF. Unlike shares of a mutual fund, which can be bought and redeemed from the issuing fund by all shareholders at a price based on NAV, shares of an ETF may be purchased or redeemed directly from the ETF solely by Authorized Participants (“APs”) and only in aggregations of a specified number of shares (“Creation Units”). In addition, shares of ETFs may be purchased and sold in the secondary market at prevailing market prices. ETFs may have a limited number of financial institutions that act as APs. To the extent that those APs exit the business, or are unable to or choose not to process creation and/or redemption orders for Creation Units, and no other AP steps forward to create and redeem ETF shares, the ETF’s shares may be more likely to trade at a premium or discount to NAV and possibly face trading halts or delisting. When a Fund buys or sells ETF shares on an exchange, it may incur certain costs, including brokerage commissions, the “bid-ask spread,” and other charges.

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Sector Risk 

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If a Fund allocates a substantial amount of its assets to one or more particular industries or to particular economic, market, or industry sectors, then economic, business, regulatory, or other developments affecting issuers in those industries or sectors may affect the Fund adversely to a greater extent than if the Fund had invested more broadly. Examples might include investments in the technology, health care, or financial sectors or in one or more industries within those sectors. A substantial investment in one or more such industries or sectors has the potential to increase the volatility of a Fund’s portfolio, and may cause the Fund to underperform other mutual funds.

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Small and Mid-Cap Company Risk 

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Small and medium-sized companies may have limited product lines, markets, or financial resources or they may depend on a few key employees. Such companies may have been recently organized and have little or no track record of success. Also, a Fund’s investment

adviser or subadviser may not have had an opportunity to evaluate such newer companies’ performance in adverse or fluctuating market conditions. Market risk and liquidity risk are particularly pronounced for stocks of small and medium-sized companies. The securities of small and medium-sized companies may trade less frequently and in smaller volume than more widely held securities. The prices of these securities may fluctuate more sharply than those of other securities, and a Fund may experience some difficulty in establishing or closing out positions in these securities at prevailing market prices. There may be less publicly available information about the issuers of these securities or less market interest in such securities than in the case of larger companies, both of which can cause significant price volatility. Some securities of small and medium-sized issuers may be illiquid or may be restricted as to resale.

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Sovereign Debt Obligations Risk 

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Investments in debt securities issued by governments or by government agencies and instrumentalities involve the risk that the governmental entities responsible for repayment may be unable or unwilling to pay interest and repay principal when due. A governmental entity’s willingness or ability to pay interest and repay principal in a timely manner may be affected by a variety of factors, including its cash flow, the size of its reserves, its access to foreign exchange, the relative size of its debt service burden to its economy as a whole, and political constraints. A governmental entity may default on its obligations or may require renegotiation or rescheduling of debt payments. Any restructuring of a sovereign debt obligation held by the Fund will likely have a significant adverse effect on the value of the obligation. In the event of default of sovereign debt, the Fund may be unable to pursue legal action against the sovereign issuer or to realize on collateral securing the debt. The sovereign debt of many non-U.S. governments, including their sub-divisions and instrumentalities, is rated below investment grade (“junk” or “high yield” bonds). Sovereign debt risk may be greater for debt securities issued or guaranteed by emerging and/or frontier market countries. At times, certain emerging and frontier market countries have declared moratoria on

the payment of principal and interest on external debt. Certain emerging and frontier market countries have experienced difficulty in servicing their sovereign debt on a timely basis, which has led to defaults and the restructuring of certain indebtedness to the detriment of debtholders.

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U.S. Government Securities Risk 

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U.S. Government securities include a variety of securities that differ in their interest rates, maturities, and dates of issue. While securities issued or guaranteed by some agencies or instrumentalities of the U.S. Government (such as the Government National Mortgage Association) are supported by the full faith and credit of the United States, securities issued or guaranteed by certain other agencies or instrumentalities of the U.S. Government (such as Federal Home Loan Banks) are supported only by the right of the issuer to borrow from the U.S. Government. Securities issued or guaranteed by certain other agencies and instrumentalities of the U.S. Government (such as Fannie Mae and Freddie Mac) are not supported by the full faith and credit of the U.S. Government and are supported only by the credit of the issuer itself. There is no assurance that the U.S. Government would provide financial support to its agencies and instrumentalities if not required to do so. For securities not backed by the full faith and credit of the United States, a Fund must look principally to the agency or instrumentality issuing or guaranteeing the securities for repayment and may not be able to assert a claim against the United States if the agency or instrumentality does not meet its commitment. Such securities may involve increased risk of loss of principal and interest compared to government debt securities that are backed by the full faith and credit of the United States. From time to time, uncertainty regarding the status of negotiations in the U.S. Government to increase the statutory debt ceiling could increase the risk that the U.S. Government may default on payments on certain U.S. Government securities, cause the credit rating of the U.S. Government to be downgraded, increase volatility in the stock and bond markets, result in higher interest rates, reduce prices of U.S. Treasury securities, and/or increase the costs of various kinds of debt. If a U.S. Government-sponsored entity is

negatively impacted by legislative or regulatory action (or lack thereof), is unable to meet its obligations, or its creditworthiness declines, the performance of each Fund that holds securities of the entity will be adversely impacted. In addition, certain governmental entities have been subject to regulatory scrutiny regarding their accounting policies and practices and other concerns that may result in legislation, changes in regulatory oversight and/or other consequences that could adversely affect the credit quality, availability, or investment character of securities issued by these entities. Investments in these securities are also subject to, among other things, interest rate risk, prepayment risk, extension risk, and the risk that the value of the securities will fluctuate in response to political, market, or economic developments.

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Valuation Risk 

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A portion of a Fund’s assets may be valued at fair value pursuant to guidelines that have been approved by the Trustees. A Fund’s assets may be valued using prices provided by a pricing service or, alternatively, a broker-dealer or other market intermediary (sometimes just one broker-dealer or other market intermediary) when other reliable pricing sources may not be available. The Fund, or persons acting on its behalf, may determine a fair value of a security based on such other information as may be available to them. There can be no assurance that any fair valuation of an investment held by a Fund will in fact approximate the price at which the Fund might sell the investment at the time. Technological issues or other service disruption issues involving third-party service providers may limit the ability of the Fund to value its investment accurately or timely. To the extent a Fund sells a security at a price lower than the price it has been using to value the security, its NAV will be adversely affected. If a Fund has overvalued securities it holds, you may pay

too much for the Fund’s shares when you buy into the Fund. If a Fund underestimates the price of its portfolio securities, you may not receive the full market value for your Fund shares when you sell.

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Value Company Risk 

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A Fund may purchase some equity securities at prices below what the investment adviser or subadviser considers to reflect their actual or potential fundamental values. The Fund bears the risk that the prices of these securities may not increase to reflect what the investment adviser or subadviser believes to be their fundamental value or that the investment adviser or subadviser may have overestimated the securities’ fundamental value or that it may take a substantial period of time to realize that value.

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When-Issued, Delayed Delivery, TBA, and Forward Commitment Transaction Risk 

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A Fund may purchase securities on a when-issued, delayed delivery, to-be-announced, or forward commitment basis. These transactions involve a commitment by a Fund to purchase securities for a predetermined price or yield, with payments and delivery taking place more than seven days in the future, or after a period longer than the customary settlement period for that type of security. These transactions involve a risk of loss if the value of the securities declines prior to the settlement date. These transactions may create investment leverage. Recently effective rules of the Financial Industry Regulatory Authority impose mandatory margin requirements for certain types of when-issued, TBA, or forward commitment transactions, with limited exceptions. Mandatory collateralization could increase the cost of such transactions and impose added operational complexity and may increase the credit risk of such transactions to a Fund.

Each Fund, other than the MML Invesco Discovery Large Cap Fund, MML Invesco Discovery Mid Cap Fund, MML iShares 60/40 Allocation Fund, MML iShares 80/20 Allocation Fund, MML Short-Duration Bond Fund, and MML U.S. Government Money Market Fund, offers the following two classes of shares: Initial Class and Service Class shares. MML Invesco Discovery Large Cap Fund, MML Invesco Discovery Mid Cap Fund, MML iShares 60/40 Allocation Fund, MML iShares 80/20 Allocation Fund, and MML Short-Duration Bond Fund offer the following two classes of shares: Class II and Service Class I shares. The MML U.S. Government Money Market Fund only offers Initial Class shares. Each Class of shares is available in connection with variable annuity contracts offered by MassMutual or its life insurance affiliates, certain variable life insurance policies offered by MassMutual or its life insurance affiliates, and in connection with certain variable life insurance policies and variable annuity contracts privately offered by MassMutual or its life insurance affiliates.

The different Classes have different fees and expenses. Different fees and expenses of a Class will affect performance of that Class. For actual

past expenses of each share class, see the “Financial Highlights” tables later in this Prospectus. For additional information, call us toll free at 1-888-309-3539 or contact your registered representative.

Except as described below, all Classes of shares of the Funds have identical voting, dividend, liquidation, and other rights, preferences, terms, and conditions. The only differences among the various Classes are: (a) each Class may be subject to different expenses specific to that Class; (b) each Class has a different Class designation; (c) each Class has exclusive voting rights with respect to matters solely affecting such Class; (d) each Class that has adopted a Rule 12b-1 Plan will bear the expense of the payments that would be made pursuant to that Rule 12b-1 Plan, and only that Class will be entitled to vote on matters pertaining to that Rule 12b-1 Plan; and (e) each Class will have different exchange privileges.

Each Class of a Fund’s shares represents an investment in the same portfolio of securities. Because the Classes will have different expenses, they will likely have different performance records and share prices.

Shares of all classes of the Funds are sold without a front-end sales charge, and none of the Funds’ shares are subject to a deferred sales charge.

Rule 12b-1 fees. 

The Funds have adopted a Rule 12b-1 Plan (the “Plan”) for their Service Class and Service Class I shares. Under the Plan, a Fund may make payments at an annual rate of up to 0.35% of the average daily net assets attributable to its Service Class or Service Class I shares. However, each Fund currently makes payments at an annual rate of 0.25% of the average daily net assets attributable to its Service Class or Service Class I shares. The Plan is a compensation plan, under which the Funds make payments to MML Distributors, LLC (the “Distributor”) for the services it provides and for the expenses it bears in connection with the distribution of shares of those classes and for the

servicing of shareholders of those classes. Because Rule 12b-1 fees are paid out of the Funds’ Service Class and Service Class I assets on an ongoing basis, they will increase the cost of your investment and may cost you more than paying other types of sales loads. All shareholders of Service Class and Service Class I shares share in the expense of Rule 12b-1 fees paid by those classes. A Fund may pay distribution fees and other amounts described in this Prospectus at a time when shares of that Fund are unavailable for purchase.

The Distributor pays out all of the Rule 12b-1 fees it receives. The Distributor pays substantially all of the amounts it receives to MassMutual. Such amounts are used to pay continuing compensation for services provided by MassMutual agents and third party firms, to compensate MassMutual for its promotional services in respect of the Funds,

and to reimburse MassMutual for expenses incurred by it in connection with promoting the Funds.

Shareholder servicing payments. 

MML Advisers pays all or a portion of the administrative and shareholder services fee it receives from each Fund, as described above under

“Management of the Funds – Investment Adviser,” to MassMutual as compensation for, or reimbursement of expenses relating to, services provided to shareholders of the Funds.

The Trust provides an investment vehicle for variable annuity contracts and variable life insurance policies offered by companies such as MassMutual. Shares of the Funds are not offered to the general public. Because these separate accounts are invested in the same underlying Funds it is possible that material conflicts could arise due to differences in tax treatment and other considerations between owners of the variable life insurance policies and owners of the variable annuity contracts. The Funds’ Trustees follow monitoring procedures which have been developed to determine whether material conflicts have arisen and what action, if any, should be taken in the event of such conflicts. If a material irreconcilable conflict should arise between owners of the variable life insurance policies and owners of the variable annuity contracts, one or the other group of owners may have to terminate its participation in the Funds. More information regarding possible conflicts between variable life insurance policies and variable annuity contracts is contained in the prospectuses for the separate accounts.

The shares of each Fund are sold at their NAV, without the deduction of any selling commission or “sales load” ​(see “Determining Net Asset Value” below). Your purchase order will be priced at the next NAV calculated after your order is received in good order by the Funds or MML Advisers. The Funds will suspend selling their shares during any period when the determination of NAV is suspended. The Funds can reject any purchase order and can suspend purchases if they believe it is in their best interest.

Certain foreign markets may be open on days when the Funds do not accept orders or price their shares. As a result, the NAV of a Fund’s shares may change on days when you will not be able to buy or sell shares.

The Funds redeem their shares at their next NAV computed after your redemption request is received in good order by the Funds or MML Advisers. You will usually receive payment for your shares within seven days after your written redemption request is received in good order. If, however, you request redemption of shares recently purchased by check, you may not receive payment until the check has been collected, which may take up to 15 days from time of purchase. Under unusual circumstances, the Funds can also suspend or postpone payment, when permitted by applicable law and regulations. Under normal circumstances, each Fund expects to meet redemption requests by using cash or cash equivalents in its portfolio and/or selling portfolio assets to generate cash. Under stressed market conditions, a Fund may pay redemption proceeds using cash obtained through borrowing arrangements that may be available from time to time. To the extent consistent with applicable laws and regulations, the Funds reserve the right to satisfy all or a portion of a redemption request by distributing securities or other property in lieu of cash (“in-kind” redemptions), under both normal and stressed market conditions. Some Funds may be limited in their ability to use assets other than cash to meet redemption requests due to restrictions on ownership of their portfolio assets. The securities distributed in an in-kind redemption will be valued in the same manner as they are valued for purposes of computing the Fund’s NAV. These securities are subject to market risk until they are sold and may increase or decrease in value prior to converting them into cash. You may incur brokerage and other transaction costs when converting the securities to cash.

Risk of Substantial Redemptions. 

If substantial numbers of shares in a Fund were to be redeemed at the same time or at approximately the same time, the Fund might be required to liquidate a significant portion of its investment portfolio quickly to meet the redemptions. A Fund might be forced to sell portfolio securities at prices or at times when it would otherwise not have sold them, resulting in a reduction in the Fund’s NAV; in addition, a substantial reduction in the size of a Fund may make it difficult for the investment

adviser or subadviser to execute its investment program successfully for the Fund for a period following the redemptions. Similarly, the prices of the portfolio securities of a Fund might be adversely affected if one or more other investment accounts managed by the investment adviser or subadviser in an investment style similar to that of the Fund were to experience substantial redemptions and those accounts were required to sell portfolio securities quickly or at an inopportune time.

The Funds are not designed to serve as vehicles for frequent trading or market timing activity. The Funds consider these activities to be abusive trading practices that can disrupt the management of a Fund in the following ways:

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by requiring the Fund to keep more of its assets liquid rather than investing them for long-term growth, resulting in lost investment opportunity; and

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by causing unplanned portfolio turnover.

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These disruptions, in turn, can result in increased expenses and can have an adverse effect on Fund performance that could impact all of a Fund’s shareholders, including long-term shareholders who do not engage in these activities. Any Funds investing in foreign securities, small capitalization securities, and below investment grade debt securities (also known as “junk” or “high yield” bonds), may be particularly susceptible to frequent trading and market timing activities and their resulting disruptions due to the difficulty of pricing such securities.

The Funds’ shareholders are variable life and variable annuity separate investment accounts owned by MassMutual and certain of its life insurance affiliates. In the case of each Fund, the separate accounts aggregate the purchase and sale information of individual contract holders and provide the information to each Fund on a net basis. Accordingly, it is difficult or impossible for the Funds to determine if a particular contract holder is engaging in frequent trading or market timing activities, and the Funds do not impose specific restrictions on trading of Fund shares in order to deter such activities.

The Trustees, on behalf of the Funds, have adopted policies and procedures with respect to frequent trading and market timing activities, under which the Funds rely on the capabilities, policies, and

procedures of MassMutual to discourage frequent trading and market timing activity, and to not accommodate frequent purchases and sales of shares within a Fund or transfers of shares between Funds. MassMutual has adopted policies and procedures to help identify those individuals or entities that may be engaging in frequent trading and/or market timing activities. MassMutual monitors trading activity to uniformly enforce its procedures. However, those who engage in such activities may employ a variety of techniques to avoid detection. Therefore, despite MassMutual’s efforts to prevent frequent trading and the market timing of Funds among the subaccounts of the separate accounts, there can be no assurance that MassMutual will be able to identify all those who trade frequently or employ a market-timing strategy, and curtail their trading in every instance.

If MassMutual determines that a contract owner’s transfer patterns reflect frequent trading or employment of a market timing strategy, MassMutual will not allow the contract owner to submit transfer requests by overnight mail, facsimile transmissions, telephone, internet, or any other type of electronic medium. Additionally, MassMutual may reject any single trade that MassMutual determines to be abusive or harmful to a Fund. It is possible that activity that MassMutual determines is not frequent trading or market timing may nonetheless adversely affect long-term shareholders of the Funds.

MassMutual, in the future, may take various restrictive actions designed to prevent the employment of a frequent trading or market timing strategy, including not accepting transfer instructions from a contract owner or other person authorized to conduct a transfer; limiting the number of transfer requests that can be made during a contract year; and requiring the value

transferred into a Fund to remain in that Fund for a particular period of time before it can be transferred out of the Fund. MassMutual will apply any restrictive action it takes uniformly to all contract owners it believes are employing a frequent trading or market timing strategy. As noted above, however, these restrictive actions may

not be effective in deterring frequent trading or market timing activity. For more information on restrictions specific to your variable life insurance policies and/or variable annuity contracts, please see the prospectus of the separate account of the specific insurance product that accompanies this Prospectus.

The NAV of each Fund’s shares is determined once daily as of the close of regular trading on the NYSE, on each Business Day. A “Business Day” is every day the NYSE is open. The NYSE normally closes at 4:00 p.m. Eastern Time, but may close earlier on some days. If the NYSE is scheduled to close early, the Business Day will be considered to end as of the time of the NYSE’s scheduled close. A Fund will not treat an intraday disruption in NYSE trading or other event that causes an unscheduled closing of the NYSE as a close of business of the NYSE for these purposes; instead, MML Advisers will determine the fair value of a Fund’s securities in accordance with MML Advisers’ fair valuation policy and procedures. The NYSE currently is not open for trading on New Year’s Day, Martin Luther King, Jr. Day, President’s Day, Good Friday, Memorial Day, Juneteenth National Independence Day, Independence Day, Labor Day, Thanksgiving Day, and Christmas Day. Each Fund calculates the NAV of each of its classes of shares by dividing the total value of the assets attributable to that class, less the liabilities attributable to that class, by the number of shares of that class that are outstanding. On holidays and other days when the NYSE is closed, each Fund’s NAV generally is not calculated and the Funds do not anticipate accepting buy or sell orders. However, the value of each Fund’s assets may still be affected on such days to the extent that a Fund holds foreign securities that trade on days that foreign securities markets are open. It is the intention of the MML U.S. Government Money Market Fund to maintain a stable NAV per share of $1.00, although this cannot be assured.

Equity securities and derivative contracts that are actively traded on a national securities exchange or contract market are valued on the basis of information furnished by a pricing service, which provides the last reported sale price, or, in the case of futures contracts, the settlement price, for securities or derivatives listed on the exchange or contract market or the official closing price on

the NASDAQ National Market System (“NASDAQ System”), or in the case of OTC securities for which an official closing price is unavailable or not reported on the NASDAQ System, the last reported bid price. Portfolio securities traded on more than one national securities exchange are valued at the last price at the close of the exchange representing the principal market for such securities. Debt securities (with the exception of debt securities held by the MML U.S. Government Money Market Fund) are valued on the basis of valuations furnished by a pricing service, which generally determines valuations taking into account factors such as institutional-size trading in similar securities, yield, quality, coupon rate, maturity, type of issue, trading characteristics, and other market data. The MML U.S. Government Money Market Fund’s debt securities are typically valued at amortized cost, but may be valued using a vendor quote if MML Advisers determines it more closely approximates current market value, in accordance with Rule 2a-7 under the 1940 Act pursuant to which the MML U.S. Government Money Market Fund must adhere to certain conditions. Shares of other open-end mutual funds are valued at their closing NAVs as reported on each Business Day.

Investments for which market quotations are readily available are marked to market daily based on those quotations. Market quotations may be provided by third-party vendors or market makers, and may be determined on the basis of a variety of factors, such as broker quotations, financial modeling, and other market data, such as market indexes and yield curves, counterparty information, and foreign exchange rates. U.S. Government and agency securities may be valued on the basis of market quotations or using a model that may incorporate market observable data such as reported sales of similar securities, broker quotes, yields, bids, offers, quoted market prices, and reference data. The fair values of OTC derivative contracts, including forward, swap, and option contracts related to interest rates, foreign

currencies, credit standing of reference entities, equity prices, or commodity prices, may be based on market quotations or may be modeled using a series of techniques, including simulation models, depending on the contract and the terms of the transaction. The fair values of asset-backed securities and mortgage-backed securities are estimated based on models that consider the estimated cash flows of each debt tranche of the issuer, established benchmark yield, and estimated tranche-specific spread to the benchmark yield based on the unique attributes of the tranche including, but not limited to, prepayment speed assumptions and attributes of the collateral.

The Trustees have designated MML Advisers as the Funds’ “valuation designee,” responsible for determining the fair value, in good faith, of securities and other instruments held by the Funds for which market quotations are not readily available or for which such market quotations or values are considered by MML Advisers or a subadviser to be unreliable (including, for example, certain foreign securities, thinly-traded securities, certain restricted securities, certain initial public offerings, or securities whose values may have been affected by a significant event). It is possible that a significant amount of a Fund’s assets will be subject to fair valuation in accordance with MML Advisers’ fair valuation policy and procedures. The fair value determined for an investment by MML Advisers may differ from recent market prices for the investment and may be significantly different from the value realized upon the sale of such investment.

The Funds may invest in securities that are traded principally in foreign markets and that trade on weekends and other days when the Funds do not price their shares. As a result, the values of the Funds’ portfolio securities may change on days when the prices of the Funds’ shares are not calculated. The prices of the Funds’ shares will reflect any such changes when the prices of the Funds’ shares are next calculated, which is the next Business Day. The Funds may use fair value pricing more frequently for securities primarily traded in foreign markets because, among other things, most foreign markets close well before the Funds value their securities. The earlier close of these foreign markets gives rise to the possibility that significant events, including broad market moves, may have occurred in the interim. The Funds’ investments may be priced based on fair values provided by a third-party vendor, based on certain factors and methodologies applied by such vendor, in the event that there is movement in the U.S. market, between the close of the foreign market and the time the Funds calculate their NAVs. All assets and liabilities expressed in foreign currencies are converted into U.S. dollars at the mean between the buying and selling rates of such currencies against the U.S. dollar at the end of each Business Day.

The Funds’ valuation methods are also described in the SAI.