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Janus Henderson Adaptive Global Allocation Fund

Ticker:	JAGAX	Class A Shares	JAGSX	Class S Shares	JAGNX	Class N Shares
	JAVCX	Class C Shares	JVGIX	Class I Shares	JVGTX	Class T Shares

Summary Prospectus dated October 27, 2023

Before you invest, you may want to review the Fund’s Prospectus, which contains more information about the Fund and its risks. You can find the Fund’s Prospectus, reports to shareholders, and other information about the Fund online at janushenderson.com/info. You can also get this information at no cost by calling a Janus Henderson representative at 1-877-335-2687 or by sending an email request to prospectusrequest@janushenderson.com.

Investment Objective

Janus Henderson Adaptive Global Allocation Fund seeks total return through growth of capital and income.

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. Each share class has different expenses, but represents an investment in the same Fund. For Class A Shares, you may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Fund or in other Janus Henderson funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial professional and in the “Purchases” section on page 42 of the Fund’s Prospectus and in the “Purchases” section on page 74 of the Fund’s Statement of Additional Information. In addition, please see Appendix A – Intermediary Sales Charge Waivers and Discounts. You may also incur brokerage commissions charged by your broker or financial intermediary when buying Class I Shares or Class N Shares of the Fund that are not reflected in the table or in the example below.

SHAREHOLDER FEES (fees paid directly from your investment)	Class A	Class C	Class S	Class I	Class N	Class T
Maximum Sales Charge (load) Imposed on Purchases (as a percentage of offering price)	5.75%	None	None	None	None	None
Maximum Deferred Sales Charge (load) (as a percentage of the lower of original purchase price or redemption proceeds)	None	1.00%	None	None	None	None
ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)	Class A	Class C	Class S	Class I	Class N	Class T
Management Fees	0.75%	0.75%	0.75%	0.75%	0.75%	0.75%
Distribution/Service (12b-1) Fees	0.25%	1.00%	0.25%	None	None	None
Other Expenses	2.25%	1.01%	1.41%	1.60%	0.75%	1.25%
Total Annual Fund Operating Expenses	3.25%	2.76%	2.41%	2.35%	1.50%	2.00%
Fee Waiver(1)	2.25%	1.06%	1.25%	1.66%	0.83%	1.09%
Total Annual Fund Operating Expenses After Fee Waiver(1)	1.00%	1.70%	1.16%	0.69%	0.67%	0.91%

(1)

The Adviser has contractually agreed to waive its investment advisory fee and/or reimburse operating expenses to the extent that the Fund’s total annual fund operating expenses (excluding the fees payable pursuant to a Rule 12b-1 plan, shareholder servicing fees, such as transfer agency fees (including out-of-pocket costs), administrative services fees and any networking/omnibus fees payable by any share class; brokerage commissions; interest; dividends; taxes; acquired fund fees and expenses; and extraordinary expenses) exceed 0.66% for at least a one-year period commencing on October 27, 2023. This contractual waiver may be terminated or modified only at the discretion of the Board of Trustees.

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and reinvest all dividends and distributions. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses are equal to the Total Annual Fund Operating Expenses After Fee Waiver for the first year and the Total Annual Fund Operating Expenses thereafter. Class C Shares automatically convert to Class A Shares after eight years. The Example

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for Class C Shares for the ten-year period reflects the conversion to Class A Shares. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If Shares are redeemed:	1 Year	3 Years	5 Years	10 Years
Class A Shares	$671	$1,319	$1,991	$3,774
Class C Shares	$273	$756	$1,365	$3,130
Class S Shares	$118	$632	$1,172	$2,651
Class I Shares	$70	$574	$1,104	$2,558
Class N Shares	$68	$392	$740	$1,719
Class T Shares	$93	$522	$977	$2,240

If Shares are not redeemed:	1 Year	3 Years	5 Years	10 Years
Class A Shares	$671	$1,319	$1,991	$3,774
Class C Shares	$173	$756	$1,365	$3,130
Class S Shares	$118	$632	$1,172	$2,651
Class I Shares	$70	$574	$1,104	$2,558
Class N Shares	$68	$392	$740	$1,719
Class T Shares	$93	$522	$977	$2,240

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 and may result in higher taxes when Fund shares are held in a taxable account. 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 293% of the average value of its portfolio.

Principal investment strategies

The Fund seeks to achieve its investment objective by allocating its assets across a portfolio of global equity, global fixed-income, and, at times, commodity-linked investments. In doing so, the Fund will attempt to reduce the risk of significant loss, or a drop in the value of the Fund’s capital that is unlikely to be regained over a full market cycle (a time period representing a significant market decline and recovery), while also participating in the upside growth of the capital markets. To achieve this objective, the Fund’s portfolio management employs a “tail managed” strategy intended to tactically shift away from assets whose downside tail risks are perceived to be increasing and toward assets whose expected tail gains are increasing. As it relates to investing, “tails” represent the outliers of a distribution of returns or, in other words, outsized future moves both to the positive and negative. Tail events typically occur more often than expected, and a tail loss or a tail gain can have a substantial impact on a portfolio’s long-term performance.

The Fund primarily invests in futures to gain indirect exposure to an underlying asset class. The Fund may also use other derivatives such as options or swaps to gain indirect exposure to an underlying asset class. Under normal circumstances, the Fund’s gross notional exposure (generally, the total value of the assets underlying a derivatives contract at the time of valuation) to derivatives is not expected to exceed 100% of the Fund’s net assets. Because of the Fund’s investments in derivatives, a significant portion of its assets may be invested directly or indirectly in short-term investments.

The Fund may invest in emerging markets, but will normally limit such investments to 30% of its net assets, measured at the time of purchase. Due to the Fund’s investment strategy, it may have relatively high portfolio turnover compared to other funds.

The Fund may invest in equity securities including common and preferred stock and securities of other investment companies. The Fund may invest across all fixed-income sectors, including U.S. and non-U.S. government debt securities (“sovereign debt”). The types of fixed-income securities in which the Fund may invest include corporate bonds, commercial paper, depositary receipts, and floating-rate securities. The Fund may also gain exposure to equity securities, fixed-income securities, and commodities through investments in exchange-traded funds (“ETFs”). The Fund may invest up to 20% of its assets in high-yield bonds (also known as “junk” bonds).

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which provide forward-looking insights into capital markets and which seek to identify indicators of market stress or potential upside. Such models include a proprietary options implied information model that monitors day-to-day movements in options prices for indicators of risk and reward between asset classes, sectors, and regions. Using the proprietary models, portfolio management will adjust the Fund’s allocations and the underlying security exposures.

•

Top-Down Macro Analysis. The top-down analysis focuses on how the Fund’s assets will be distributed between the global equity and global fixed-income asset classes, and, at times, the commodity asset class. Portfolio management monitors expected tail gains and losses across the equity, fixed-income, and commodity asset classes. Portfolio management intends to periodically adjust the Fund’s asset allocation to mitigate downside risk exposure that is perceived to be elevated and obtain exposure to upside gains. Accordingly, the Fund’s allocation to global equity investments, global fixed-income investments, and, at times, commodity-linked investments, will likely shift periodically to minimize exposure to tail losses and enhance exposure to tail gains. The periodic shifts in the Fund’s asset allocation may significantly impact the Fund’s risk profile.

•

Bottom-Up Risk/Reward Analysis. The bottom-up analysis is designed to identify the underlying security exposures that comprise the Fund’s equity, fixed-income, and commodity asset classes, and periodically rebalance the Fund’s portfolio to maximize exposure to securities that are expected to provide tail gains while minimizing exposure to securities that are expected to provide tail losses. Within the Fund’s equity component, portfolio management intends to adjust the portfolio’s sector, currency, and regional exposures away from market capitalization weights based on an evaluation of expected tail loss and gain. Within the Fund’s fixed-income component, portfolio management intends to adjust the portfolio’s credit, duration, and regional exposures using the same analysis. Within the Fund’s commodity asset class, portfolio management intends to adjust individual commodity or sector exposures when appropriate using the same analysis.

In pursuing its investment objective, the Fund will have exposure to investments that are economically tied to a number of countries throughout the world. A security is deemed to be economically tied to a country or countries if one or more of the following tests are met: (i) the company is organized in, or its primary business office or principal trading market of its equity is located in, the country; (ii) a majority of the company’s revenues are derived from one or more countries; or (iii) a majority of the company’s assets are located in one or more countries.

The Fund may also use derivatives to enhance returns and to hedge portfolio risks. With regard to using derivatives for hedging purposes, the Fund may use foreign exchange contracts or other similar instruments to reduce the impact of foreign exchange rate changes on the Fund’s value. The Fund may also engage in short sales.

The Fund may seek to earn additional income through lending its securities to certain qualified broker-dealers and institutions on a short-term or long-term basis, in an amount equal to up to one-third of its total assets as determined at the time of the loan origination.

Principal investment risks

The biggest risk is that the Fund’s returns will vary, and you could lose money. The Fund is designed for long-term investors seeking a portfolio which includes exposure to equity securities (such as stocks or any other security representing an ownership interest), fixed-income securities (such as bonds, notes, and debentures), and commodities, and which involves the use of derivatives. The principal risks associated with investing in the Fund are set forth below.

Market Risk. The value of the Fund’s portfolio may decrease due to short-term market movements and over more prolonged market downturns. As a result, the Fund’s net asset value may fluctuate and it may be more difficult to value or sell the Fund’s holdings.Market risk may affect a single issuer, industry, economic sector, or the market as a whole. Market risk may be magnified if certain social, political, economic, and other conditions and events (such as terrorism, conflicts, including related sanctions, social unrest, natural disasters, epidemics and pandemics, including COVID-19) adversely interrupt the global economy and financial markets. It is important to understand that the value of your investment may fall, sometimes sharply, in response to changes in the market, and you could lose money.

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movements. In addition, there may be at times an imperfect correlation between the movement in the prices of a derivatives contract and the value of an underlying instrument. Derivatives used for hedging purposes may reduce or eliminate gains or cause losses if the market moves in a manner different from that anticipated by portfolio management or if the cost of the derivative outweighs the benefit of the hedge.

Portfolio Management Risk. The Fund is an actively managed investment portfolio and is therefore subject to the risk that the investment strategies employed for the Fund may fail to produce the intended results. The Fund may underperform its benchmark index or other mutual funds with similar investment objectives.

Investment Process Risk. Portfolio management uses certain proprietary models, including a proprietary options implied information model, to implement the Fund’s investment strategy. These models may not be successful in identifying how the Fund’s allocations and underlying security exposures should be adjusted in order to reduce the risk of loss while participating in the upside growth of capital markets. As a result, there is a risk that the Fund may underperform its benchmark if these models do not correctly identify indicators of risk and reward between asset classes, sectors, and regions. Further, while the use of these models and subsequent portfolio reallocations are intended to benefit investors that invest in the Fund, these techniques could in certain cases have a detrimental effect on the Fund, including increasing portfolio turnover (and related transactions costs) and causing the Fund to incur taxable gains.

Sovereign Debt Risk. Investments in U.S. and non-U.S. government debt especially the debt of certain emerging market countries, can involve a high degree of risk, including the risk that the governmental entity that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or to pay the interest on its sovereign debt in a timely manner.A sovereign debtor’s willingness or ability to satisfy its debt obligation may be affected by various factors including, but not limited to, its cash flow situation, the extent of its foreign currency reserves, the availability of foreign exchange when a payment is due, and the relative size of its debt position in relation to its economy as a whole.In the event of default, there may be limited or no legal remedies for collecting sovereign debt and there may be no bankruptcy proceedings through which the Fund may collect all or part of the sovereign debt that a governmental entity has not repaid.In addition, to the extent the Fund invests in non-U.S. sovereign debt, it may be subject to currency risk.

Commercial Paper Risk. Commercial paper is a debt obligation usually issued by corporations in order to finance their current operations. Commercial paper is usually repaid at maturity by the issuer from the proceeds of the issuance of new commercial paper. As a result, investments in commercial paper are subject to the risk the issuer cannot issue enough new commercial paper to satisfy its outstanding commercial paper, also known as rollover risk. In addition, under certain circumstances commercial paper may become illiquid or may suffer from reduced liquidity.

Exchange-Traded Funds Risk. The Fund may invest in ETFs to gain exposure to a particular portion of the market. ETFs are typically open-end investment companies, which may seek to track the performance of a specific index or be actively managed. ETFs are traded on a national securities exchange at market prices that may vary from the net asset value of their underlying investments. Accordingly, there may be times when an ETF trades at a premium or discount to its net asset value. When the Fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. The Fund is also subject to the risks associated with the securities in which the ETF invests.

Equity Securities Risk. The Fund’s use of equity securities, such as common stocks and preferred stocks, creates additional risk as those securities typically have greater price volatility than fixed-income securities and may not perform as expected. In addition, equity securities may decline in value in response to general market and economic conditions, which may reduce the Fund’s returns.

4 | Janus Investment Fund

federal, regional, and local levels in developing or emerging market countries may be less transparent, inconsistently enforced, and subject to change. Emerging markets may be subject to a higher degree of corruption and fraud than developed markets, and financial institutions and transaction counterparties may have less financial sophistication, creditworthiness, and/or resources than participants in developed markets. In addition, the Fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of the Fund’s investments.

High-Yield Bond Risk. High-yield bonds (also known as “junk” bonds) are considered speculative and may be more sensitive than other types of bonds to economic changes, political changes, or adverse developments specific to the company that issued the bond, which may adversely affect their value.

Fixed-Income Securities Risk. Fixed-income securities are generally subject to the following risks:

•

Interest rate risk is the risk that prices of bonds and other fixed-income securities will increase as interest rates fall and decrease as interest rates rise. Changing interest rates have unpredictable effects on the markets and may expose fixed-income and related markets to heightened volatility.

•

Credit risk is the risk that the credit strength of an issuer of a fixed-income security will weaken and/or that the issuer will be unable to make timely principal and interest payments and that the security may go into default.

•

Prepayment risk is the risk that, during periods of falling interest rates, certain debt obligations may be paid off quicker than originally anticipated, which may cause the Fund to reinvest its assets in securities with lower yields, resulting in a decline in the Fund’s income or return potential.

•

Extension risk is the risk that, during periods of rising interest rates, certain debt obligations may be paid off substantially slower than originally anticipated, and as a result, the value of those obligations may fall.

•

Valuation risk is the risk that one or more of the fixed-income securities in which the Fund invests are priced differently than the value realized upon such security’s sale. In times of market instability, valuation may be more difficult. Valuation may also be affected by changes in the issuer’s financial strength, the market’s perception of such strength, or in the credit rating of the issuer or the security.

•

Liquidity risk is the risk that fixed-income securities may be difficult or impossible to sell at the time that portfolio management would like or at the price portfolio management believes the security is currently worth. Consequently, the Fund may have to accept a lower price to sell a security, sell other securities to raise cash, or give up an investment opportunity, any of which could have a negative effect on the Fund’s performance. In unusual market conditions, even normally liquid securities may be affected by a degree of liquidity risk (i.e., if the number and capacity of traditional market participants is reduced).

Foreign Exposure Risk. Foreign markets can be more volatile than the U.S. market. As a result, the Fund’s returns and net asset value may be affected by fluctuations in currency exchange rates or political or economic conditions in a particular country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio.

Portfolio Turnover Risk. Increased portfolio turnover may result in higher costs, which may have a negative effect on the Fund’s performance. In addition, higher portfolio turnover may result in the acceleration of capital gains and the recognition of greater levels of short-term capital gains, which are taxed at ordinary federal income tax rates when distributed to shareholders.

Commodity-Linked Investments Risk. The Fund may invest, directly or indirectly, in various commodity-linked investments that provide exposure to the commodities markets. Such exposure may subject the Fund to greater volatility than investments in traditional securities. The value of a given commodity-linked investment typically is based upon the price movements of a physical commodity (such as heating oil, livestock, agricultural products, or precious metals), a commodity futures contract or commodity index, or some other readily measurable economic variable. The value of commodity-linked instruments may therefore be affected by changes in overall market movements, volatility of a commodity index, changes in interest rates, or other factors affecting a particular industry or commodity such as drought, floods, weather, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments.

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Short Sales Risk. Short sales are speculative transactions and involve special risks, including a greater reliance on the ability to accurately anticipate the future value of a security. The Fund will suffer a loss if it sells a security short and the value of the security rises rather than falls. The Fund’s losses are potentially unlimited in a short sale transaction. The use of short sales may also cause the Fund to have higher expenses than those of other funds. In addition, due to the investment process of long and short positions, the Fund may be subject to additional transaction costs that may lower the Fund’s returns. The Fund’s use of short sales may also have a leveraging effect on the Fund’s portfolio and may increase losses and the volatility of returns.

Depositary Receipts Risk. Depositary receipts are generally subject to the same sort of risks as direct investments in a foreign country, such as currency risk, market risk, and foreign exposure risk, because their values depend on the performance of a foreign security denominated in its home currency.

Smaller Sized Fund Risk. Because the Fund has a small asset base, large inflows and outflows may have a disproportionate impact, negative or positive, on the Fund’s performance, which may be more volatile than that of a larger fund. If a smaller fund were to fail to attract sufficient assets to achieve or maintain economies of scale, any resulting liquidation could create negative transaction costs for the fund and tax consequences for investors.

Large Shareholder Risk. To the extent a substantial percentage of the shares of the Fund are held by a small number of shareholders, including “fund of funds” or accounts over which the Adviser has investment discretion, the Fund is subject to the risk that these shareholders will purchase or redeem the Fund’s shares in large amounts rapidly or unexpectedly, including as a result of an asset allocation decision made by the Adviser. These transactions could adversely affect the ability of the Fund to conduct its investment program.

Securities Lending Risk. There is the risk that when portfolio securities are lent, the securities may not be returned on a timely basis, and the Fund may experience delays and costs in recovering the security or gaining access to the collateral provided to the Fund to collateralize the loan. If the Fund is unable to recover a security on loan, the Fund may use the collateral to purchase replacement securities in the market. There is a risk that the value of the collateral could decrease below the cost of the replacement security by the time the replacement investment is made, resulting in a loss to the Fund.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Performance information

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time.The bar chart depicts the change in performance from year to year during the periods indicated. The bar chart figures do not include any applicable sales charges that an investor may pay when they buy or sell Class A Shares or Class C Shares of the Fund. If sales charges were included, the returns would be lower. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index, as well as to one or more supplemental indices that have investment characteristics similar to those of the Fund. All figures assume reinvestment of dividends and distributions.For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

The Fund’s past performance (before and after taxes) does not necessarily indicate how it will perform in the future.Updated performance information is available at janushenderson.com/performance or by calling 1-877-335-2687.

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Annual Total Returns for Class I Shares (calendar year-end)

Best Quarter:

4th Quarter 2020

11.00%

Worst Quarter:

1st Quarter 2020

– 12.65%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2023 was 5.90%.

Average Annual Total Returns (periods ended 12/31/22)
	1 Year	5 Years	Since Inception (6/23/15)
Class I Shares
Return Before Taxes	– 11.28%	2.42%	3.63%
Return After Taxes on Distributions	– 11.66%	0.61%	1.97%
Return After Taxes on Distributions and Sale of Fund Shares(1)	– 6.62%	1.33%	2.28%
MSCI All Country World Indexsm (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 18.36%	5.23%	6.35%
Adaptive Global Allocation 60/40 Index (Hedged) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 15.32%	3.59%	4.61%
Bloomberg Global Aggregate Bond Index (USD Hedged) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 11.22%	0.36%	1.37%
Class A Shares
Return Before Taxes(2)	– 16.64%	0.92%	2.54%
MSCI All Country World Indexsm (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 18.36%	5.23%	6.35%
Adaptive Global Allocation 60/40 Index (Hedged) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 15.32%	3.59%	4.61%
Bloomberg Global Aggregate Bond Index (USD Hedged) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 11.22%	0.36%	1.37%
Class C Shares
Return Before Taxes(3)	– 12.35%	2.05%	3.04%
MSCI All Country World Indexsm (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 18.36%	5.23%	6.35%
Adaptive Global Allocation 60/40 Index (Hedged) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 15.32%	3.59%	4.61%
Bloomberg Global Aggregate Bond Index (USD Hedged) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 11.22%	0.36%	1.37%

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Average Annual Total Returns (periods ended 12/31/22)
	1 Year	5 Years	Since Inception (6/23/15)
Class S Shares
Return Before Taxes	– 11.33%	2.30%	3.42%
MSCI All Country World Indexsm (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 18.36%	5.23%	6.35%
Adaptive Global Allocation 60/40 Index (Hedged) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 15.32%	3.59%	4.61%
Bloomberg Global Aggregate Bond Index (USD Hedged) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 11.22%	0.36%	1.37%
Class N Shares
Return Before Taxes	– 11.33%	2.45%	3.66%
MSCI All Country World Indexsm (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 18.36%	5.23%	6.35%
Adaptive Global Allocation 60/40 Index (Hedged) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 15.32%	3.59%	4.61%
Bloomberg Global Aggregate Bond Index (USD Hedged) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 11.22%	0.36%	1.37%
Class T Shares
Return Before Taxes	– 11.53%	2.22%	3.43%
MSCI All Country World Indexsm (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 18.36%	5.23%	6.35%
Adaptive Global Allocation 60/40 Index (Hedged) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 15.32%	3.59%	4.61%
Bloomberg Global Aggregate Bond Index (USD Hedged) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 11.22%	0.36%	1.37%

(1)

If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

(2)

Calculated assuming maximum permitted sales loads.

(3)

The one year return is calculated to include the contingent deferred sales charge.

The Fund’s primary benchmark index is the MSCI All Country World Index. The Fund also compares its performance to the Adaptive Global Allocation 60/40 Index (Hedged) and the Bloomberg Global Aggregate Bond Index (USD Hedged). The indices are described below.

•

The MSCI All Country World Index is designed to measure equity market performance in global developed and emerging markets.

•

The Adaptive Global Allocation 60/40 Index (Hedged) is an internally-calculated, hypothetical combination of total returns from the MSCI All Country World Index (60%) and the Bloomberg Global Aggregate Bond Index (40%).

•

The Bloomberg Global Aggregate Bond Index (USD Hedged) is a broad-based measure of the global investment grade fixed-rate debt markets.

After-tax returns are calculated using the historically highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on your individual tax situation and may differ from those shown in the preceding table. The after-tax return information shown above does not apply to Fund shares held through a tax-advantaged account, such as a 401(k) plan or an IRA.

After-tax returns are only shown for Class I Shares of the Fund. After-tax returns for the other classes of Shares will vary from those shown for Class I Shares due to varying sales charges (as applicable), fees, and expenses among the classes.

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Management

Investment Adviser: Janus Henderson Investors US LLC

Portfolio Management: Ashwin Alankar, Ph.D., is Executive Vice President and Portfolio Manager of the Fund, which he has managed or co-managed since inception.

Purchase and sale of Fund shares

Minimum Investment Requirements

Class A Shares, Class C Shares*, Class S Shares, and Class T Shares
Non-retirement accounts	$2,500**
Certain tax-advantaged accounts or UGMA/UTMA accounts	$500
Class I Shares
Institutional investors (investing directly with the Fund)	$1,000,000
Through an intermediary institution
• non-retirement accounts	$2,500 †
• certain tax-advantaged accounts or UGMA/UTMA accounts	$500 †
Class N Shares
Retirement investors (investing through an adviser-assisted, employer-sponsored retirement plan)	None
Retail investors (investing through a financial intermediary omnibus account)	$2,500***
Institutional investors (investing directly with the Fund)	$1,000,000

†

Exceptions to these minimums may apply for certain tax-advantaged, tax-qualified and retirement plans, including health savings accounts, accounts held through certain wrap programs, and certain retail brokerage accounts.

The maximum purchase in Class C Shares is $500,000 for any single purchase.

Class A, Class C, Class S, and Class T shares held through certain supermarket and/or self-directed brokerage accounts, or through wrap programs, may not be subject to these minimums. Please contact your financial intermediary for more information.

***

Investors in certain tax-advantaged accounts or accounts held through certain wrap programs or bank trust platforms may not be subject to this minimum.

Purchases, exchanges, and redemptions can generally be made only through institutional channels, such as financial intermediaries and retirement platforms. Class I Shares may be purchased directly by certain institutional investors who established Class I Shares accounts before August 4, 2017. You should contact your financial intermediary or refer to your plan documents for information on how to invest in the Fund. Requests must be received in good order by the Fund or its agents (financial intermediary or plan sponsor, if applicable) prior to the close of the trading session of the New York Stock Exchange in order to receive that day’s net asset value. For additional information, refer to “Purchases,” “Exchanges,” and/or “Redemptions” in the Prospectus.

Tax information

The Fund’s distributions are taxable, and will be taxed as ordinary income or capital gains, unless you are investing through a tax-advantaged arrangement, such as a 401(k) plan or an individual retirement account (in which case you may be taxed upon withdrawal of your investment from such account).

Payments to broker-dealers and other financial intermediaries

If you purchase Class A Shares, Class C Shares, Class S Shares, Class I Shares, or Class T Shares of the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund or its distributor (or its affiliates) may pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your salesperson to recommend the Fund over another investment or to recommend one share class over another. There is some regulatory uncertainty concerning whether marketing support or other similar payments may be made or received in connection with Class I Shares where a financial intermediary has imposed its own sales charges or transaction fees. As a result, based on future regulatory developments, such payments may be terminated, or the Fund may prohibit financial intermediaries from imposing such sales charges or transaction fees in connection with Class I Shares. Ask your salesperson or visit your financial intermediary’s website for more information.

9 | Janus Henderson Adaptive Global Allocation Fund

[JANUS HENDERSON LOGO]

Janus Henderson Adaptive Global Allocation Fund

Ticker:

JAGDX

Class D Shares

Summary Prospectus dated October 27, 2023

Before you invest, you may want to review the Fund’s Prospectus, which contains more information about the Fund and its risks. You can find the Fund’s Prospectus, reports to shareholders, and other information about the Fund online at janushenderson.com/reports. You can also get this information at no cost by calling a Janus Henderson representative at 1-800-525-3713 or by sending an email request to prospectusorder@janushenderson.com.

Investment Objective

Janus Henderson Adaptive Global Allocation Fund seeks total return through growth of capital and income.

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.

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)		Class D
Management Fees		0.75%
Other Expenses		1.11%
Total Annual Fund Operating Expenses		1.86%
Fee Waiver(1)		1.05%
Total Annual Fund Operating Expenses After Fee Waiver(1)		0.81%

(1)

The Adviser has contractually agreed to waive its investment advisory fee and/or reimburse operating expenses to the extent that the Fund’s total annual fund operating expenses (excluding shareholder servicing fees, such as transfer agency fees (including out-of-pocket costs), brokerage commissions, interest, dividends, taxes, acquired fund fees and expenses, and extraordinary expenses) exceed 0.66% for at least a one-year period commencing on October 27, 2023. This contractual waiver may be terminated or modified only at the discretion of the Board of Trustees.

EXAMPLE:

The Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated, reinvest all dividends and distributions, and then redeem all of your Shares at the end of each period. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses are equal to the Total Annual Fund Operating Expenses After Fee Waiver for the first year and the Total Annual Fund Operating Expenses thereafter. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

	1 Year	3 Years	5 Years	10 Years
Class D Shares	$83	$483	$908	$2,094

Principal investment strategies

1 | Janus Henderson Adaptive Global Allocation Fund

To implement the strategy, portfolio management utilizes two complementary processes: a “top-down” macro analysis and a “bottom-up” risk/reward analysis, each of which are described below. These processes each employ certain proprietary models which provide forward-looking insights into capital markets and which seek to identify indicators of market stress or potential upside. Such models include a proprietary options implied information model that monitors day-to-day movements in options prices for indicators of risk and reward between asset classes, sectors, and regions. Using the proprietary models, portfolio management will adjust the Fund’s allocations and the underlying security exposures.

•

2 | Janus Investment Fund

Principal investment risks

Derivatives Risk. The Fund may use derivatives to enhance returns and for hedging purposes. Derivatives can be volatile and involve risks in addition to the risks of the underlying referenced securities or asset. Gains or losses from a derivative investment can be substantially greater than the derivative’s original cost and can therefore involve leverage. Leverage may cause the Fund to be more volatile than if it had not used leverage. Derivatives entail the risk that the counterparty will default on its payment obligations. Investments in derivatives are subject to the risk of loss caused by unanticipated market movements. In addition, there may be at times an imperfect correlation between the movement in the prices of a derivatives contract and the value of an underlying instrument. Derivatives used for hedging purposes may reduce or eliminate gains or cause losses if the market moves in a manner different from that anticipated by portfolio management or if the cost of the derivative outweighs the benefit of the hedge.

3 | Janus Henderson Adaptive Global Allocation Fund

underlying investments. Accordingly, there may be times when an ETF trades at a premium or discount to its net asset value. When the Fund invests in an ETF, in addition to directly bearing the expenses associated with its own operations, it will bear a pro rata portion of the ETF’s expenses. The Fund is also subject to the risks associated with the securities in which the ETF invests.

Emerging Markets Risk. Emerging market securities involve a number of risks, which may result from less government supervision and regulation of business and industry practices (including the potential lack of strict finance and accounting controls and standards), stock exchanges, brokers, and listed companies. Information about emerging market companies, including financial information, may be less available or reliable and the Adviser’s ability to conduct due diligence with respect to such companies may be limited. Accordingly, these investments may be potentially more volatile in price and less liquid than investments in developed securities markets, resulting in greater risk to investors. There is a risk in developing countries that a current or future economic or political crisis could lead to price controls, forced mergers of companies, expropriation or confiscatory taxation, imposition or enforcement of foreign ownership limits, seizure, nationalization, sanctions or imposition of restrictions by various governmental entities on investment and trading, or creation of government monopolies, any of which may have a detrimental effect on the Fund’s investments. In addition, the taxation systems at the federal, regional, and local levels in developing or emerging market countries may be less transparent, inconsistently enforced, and subject to change. Emerging markets may be subject to a higher degree of corruption and fraud than developed markets, and financial institutions and transaction counterparties may have less financial sophistication, creditworthiness, and/or resources than participants in developed markets. In addition, the Fund’s investments may be denominated in foreign currencies and therefore, changes in the value of a country’s currency compared to the U.S. dollar may affect the value of the Fund’s investments.

Fixed-Income Securities Risk. Fixed-income securities are generally subject to the following risks:

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4 | Janus Investment Fund

country. In some foreign markets, there may not be protection against failure by other parties to complete transactions. It may not be possible for the Fund to repatriate capital, dividends, interest, and other income from a particular country or governmental entity. In addition, a market swing in one or more countries or regions where the Fund has invested a significant amount of its assets may have a greater effect on the Fund’s performance than it would in a more geographically diversified portfolio.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Performance information

The following information provides some indication of the risks of investing in the Fund by showing how the Fund’s performance has varied over time.The bar chart depicts the change in performance from year to year during the periods indicated. The table compares the Fund’s average annual returns for the periods indicated to a broad-based securities market index, as well as to one or more supplemental indices that have investment characteristics similar to those of the Fund. All

5 | Janus Henderson Adaptive Global Allocation Fund

figures assume reinvestment of dividends and distributions.For certain periods, the Fund’s performance reflects the effect of expense waivers. Without the effect of these expense waivers, the performance shown would have been lower.

Annual Total Returns for Class D Shares (calendar year-end)

Best Quarter:

4th Quarter 2020

11.26%

Worst Quarter:

1st Quarter 2020

– 12.46%

The Fund’s year-to-date return as of the calendar quarter ended September 30, 2023 was 5.90%.

Average Annual Total Returns (periods ended 12/31/22)
	1 Year	5 Years	Since Inception (6/23/15)
Class D Shares
Return Before Taxes	– 11.41%	2.34%	3.51%
Return After Taxes on Distributions	– 11.75%	0.56%	1.88%
Return After Taxes on Distributions and Sale of Fund Shares(1)	– 6.70%	1.28%	2.20%
MSCI All Country World Indexsm (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 18.36%	5.23%	6.35%
Adaptive Global Allocation 60/40 Index (Hedged) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 15.32%	3.59%	4.61%
Bloomberg Global Aggregate Bond Index (USD Hedged) (reflects no deduction for expenses, fees, or taxes, except foreign withholding taxes)	– 11.22%	0.36%	1.37%

(1)

If the Fund incurs a loss, which generates a tax benefit, the Return After Taxes on Distributions and Sale of Fund Shares may exceed the Fund’s other return figures.

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The MSCI All Country World Index is designed to measure equity market performance in global developed and emerging markets.

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The Bloomberg Global Aggregate Bond Index (USD Hedged) is a broad-based measure of the global investment grade fixed-rate debt markets.

6 | Janus Investment Fund

Management

Investment Adviser: Janus Henderson Investors US LLC

Portfolio Management: Ashwin Alankar, Ph.D., is Executive Vice President and Portfolio Manager of the Fund, which he has managed or co-managed since inception.

Purchase and sale of Fund shares

Minimum Investment Requirements
To open a new regular Fund account	$2,500
To open a new regular Fund account with an automatic investment program of $50 per month	$100
To open a new UGMA/UTMA account, Coverdell Education Savings Account, or a retirement Fund account
• without an automatic investment program	$1,000
• with an automatic investment program of $50 per month	$100
To add to any existing type of Fund account without an automatic investment program	$50

You may generally purchase, exchange, or redeem Fund Shares on any business day by written request, wire transfer, telephone, and in most cases, online at janushenderson.com/individual. You may conduct transactions by mail (Janus Henderson, P.O. Box 219109, Kansas City, MO 64121-9109), or by telephone at 1-800-525-3713. Purchase, exchange, or redemption requests must be received in good order by the Fund or its agents prior to the close of the trading session of the New York Stock Exchange in order to receive that day’s net asset value. For additional information, refer to “To Open an Account or Buy Shares,” “To Exchange Shares,” and/or “To Sell Shares” in the Prospectus.

Tax information

Payments to broker-dealers and other financial intermediaries

With respect to share classes not offered in this Prospectus, the Fund or its distributor (or its affiliates) pay select broker-dealer firms or other financial intermediaries for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing a broker-dealer or other intermediary or a salesperson to recommend the Fund over another investment or to recommend one share class over another.

7 | Janus Henderson Adaptive Global Allocation Fund