Share class (Symbol): A (SMGXX), A2 (SMTXX), N (LGMXX), Service Shares (LGSXX)

WESTERN ASSET

GOVERNMENT RESERVES

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 and other information about the fund, including the fund’s statement of additional information and shareholder reports, online at www.leggmason.com/moneymarketfundsliterature. You can also get this information at no cost by calling the fund at 1-877-721-1926 or 1-203-703-6002 or by sending an e-mail request to prospectus@leggmason.com, or from your financial intermediary. The fund’s Prospectus and statement of additional information, each dated December  29, 2020 (as may be amended or supplemented from time to time), and the independent registered public accounting firm’s report and financial statements in the fund’s annual report to shareholders, dated August 31, 2020, are incorporated by reference into this Summary Prospectus.

Beginning in or after February 2021, as permitted by regulations adopted by the Securities and Exchange Commission, the fund intends to no longer mail paper copies of the fund’s shareholder reports, unless you specifically request paper copies of the reports from the fund or from your Service Agent or financial intermediary (such as a broker-dealer or bank). Instead, the reports will be made available on a website, and you will be notified by mail each time a report is posted and provided with a website link to access the report. If you already elected to receive shareholder reports electronically (“e-delivery”), you will not be affected by this change and you need not take any action. If you have not already elected e-delivery, you may elect to receive shareholder reports and other communications from the fund electronically by contacting your Service Agent or, if you are a direct shareholder with the fund, by calling 1-877-721-1926. You may elect to receive all future reports in paper free of charge. If you invest through a Service Agent, you can contact your Service Agent to request that you continue to receive paper copies of your shareholder reports. That election will apply to all Legg Mason funds held in your account at that Service Agent. If you are a direct shareholder with the fund, you can call the fund at 1-877-721-1926, or write to the fund by regular mail at Legg Mason Funds, P.O. Box 9699, Providence, RI 02940-9699 or by express, certified or registered mail to Legg Mason Funds, 4400 Computer Drive, Westborough, MA 01581 to let the fund know you wish to continue receiving paper copies of your shareholder reports. That election will apply to all Legg Mason Funds held in your account held directly with the fund complex.

Investment objective

The fund seeks maximum current income to the extent consistent with preservation of capital and the maintenance of liquidity.

Fees and expenses of the fund

The accompanying table describes the fees and expenses that you may pay if you buy, hold and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.

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. The example assumes:

Although your actual costs may be higher or lower, based on these assumptions your costs would be:

The fund is a feeder fund that invests in securities through an underlying mutual fund, Government Portfolio, which has the same investment objective and strategies as the fund. This structure is sometimes known as a “master/feeder” structure.

Principal investment strategies

The fund is a money market fund that invests exclusively in short-term U.S. government obligations, including U.S. Treasuries and securities issued or guaranteed by the U.S. government or its agencies, authorities, instrumentalities or sponsored entities and in repurchase agreements collateralized by government obligations. These securities may pay

interest at fixed, floating or adjustable rates or may be issued at a discount. U.S. government obligations are not necessarily backed by the full faith and credit of the United States. The fund may also hold cash for cash management and defensive purposes. Although the fund invests in U.S. government obligations, an investment in the fund is neither insured nor guaranteed by the U.S. government.

The fund invests in securities that, at the time of purchase, are rated by one or more rating agencies in the highest short term rating category or, if not rated, are determined by the subadviser to be of equivalent quality.

As noted above, the fund invests exclusively in short-term U.S. government obligations and in repurchase agreements collateralized by government obligations. Therefore, the fund meets the requirement under Rule 2a-7 under the Investment Company Act of 1940, as amended, that a government money market fund invest at least 99.5% of its total assets in U.S. government obligations, cash, and/or repurchase agreements that are fully collateralized by U.S. government obligations or cash. In addition, the fund meets the requirement under Rule 35d-1 under the Investment Company Act of 1940, as amended, that a fund that includes the term “government” in its name invest, under normal circumstances, at least 80% of its net assets in U.S. government obligations and/or repurchase agreements that are collateralized by U.S. government obligations.

As a government money market fund, the fund tries to maintain a share price of $1.00. Under Rule 2a-7 of the Investment Company Act of 1940, as amended, the fund must follow strict rules as to the credit quality, liquidity, diversification and maturity of its investments. Where required by these rules, the fund’s subadviser or Board of Trustees (the “Board”) will decide whether a security should be held or sold in the event of credit downgrades or certain other events occurring after purchase.

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 deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The fund’s sponsor has no legal obligation to provide financial support to the fund, and you should not expect that the sponsor will provide financial support to the fund at any time.

If one or more money market funds were to incur a sizeable loss or impose fees on redemptions or suspend redemptions, there could be significant redemptions from money market funds in general, potentially driving the market prices of money market instruments down and adversely affecting market liquidity.

The fund does not currently intend to avail itself of the ability to impose “liquidity fees” and/or “gates” on fund redemptions, as permitted under Rule 2a-7. However, the Board reserves the right, with notice to shareholders, to change this policy, thereby permitting the fund to impose such fees and gates in the future.

The fund could underperform other short-term debt instruments or money market funds, or you could lose money, as a result of risks such as:

Market and interest rate risk. The market prices of the fund’s securities may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic or political conditions, tariffs and trade disruptions, inflation, changes in interest rates, lack of liquidity in the bond markets or adverse investor sentiment. While the fund seeks to maintain a $1.00 share price, if the market price of the fund’s securities fall, the value of your investment could decline. Market prices will generally go down when interest rates rise. A rise in rates tends to have a greater impact on the prices of longer term securities. A general rise in interest rates may cause investors to move out of fixed income securities on a large scale, which could adversely affect the price and liquidity of fixed income securities and could also result in increased redemptions from the fund. The fund may face a heightened level of interest rate risk due to changes in monetary policy. When interest rates go down, the fund’s yield will decline. Also, when interest rates decline, investments made by the fund may pay a lower interest rate, which would reduce the income received by the fund. In recent years, the U.S. has experienced historically low interest rates, increasing the exposure of debt securities to the risks associated with rising interest rates.

Market events risk. The market values of securities or other assets will fluctuate, sometimes sharply and unpredictably, due to changes in general market conditions, overall economic trends or events, governmental actions or intervention, actions taken by the U.S. Federal Reserve or foreign central banks, market disruptions caused by trade disputes or other factors, political developments, investor sentiment, the global and domestic effects of a pandemic, and other factors that may or may not be related to the issuer of the security or other asset. Economies and financial markets throughout the world are increasingly interconnected. Economic, financial or political events, trading and tariff arrangements, public health events, terrorism, natural disasters and other circumstances in one country or region could have profound impacts on global economies or markets. As a result, whether or not the fund invests in securities of issuers located in or with significant exposure to the countries directly affected, the value and liquidity of the fund’s investments may be negatively affected.

The rapid and global spread of a highly contagious novel coronavirus respiratory disease, designated COVID-19, has resulted in extreme volatility in the financial markets and severe losses; reduced liquidity of many instruments; restrictions on international and, in some cases, local travel; significant disruptions to business operations (including business closures); strained healthcare systems; disruptions to supply chains, consumer demand and employee availability; and widespread uncertainty regarding the duration and long-term effects of this pandemic. Some sectors of the economy and individual issuers have experienced particularly large losses. In addition, the COVID-19 pandemic may result in a sustained domestic or even global economic downturn or recession, domestic and foreign political and social instability, damage to diplomatic and international trade relations and increased volatility and/or decreased liquidity in the securities markets. Developing or emerging market countries may be more impacted by the COVID-19 pandemic as they may have less established health care systems and may be less able to control or mitigate the effects of the pandemic. The impact of the COVID-19 pandemic may last for an extended period of time. The ultimate economic fallout from the pandemic, and the

long-term impact on economies, markets, industries and individual issuers, are not known. The U.S. government and the Federal Reserve, as well as certain foreign governments and central banks, are taking extraordinary actions to support local and global economies and the financial markets in response to the COVID-19 pandemic, including by pushing interest rates to very low levels. These actions have resulted in significant expansion of public debt, including in the U.S. This and other government intervention into the economy and financial markets to address the COVID-19 pandemic may not work as intended, particularly if the efforts are perceived by investors as being unlikely to achieve the desired results. Government actions to mitigate the economic impact of the pandemic have resulted in a large expansion of government deficits and debt, the long term consequences of which are not known. The COVID-19 pandemic could adversely affect the value and liquidity of the fund’s investments, impair the fund’s ability to satisfy redemption requests, and negatively impact the fund’s performance. In addition, the outbreak of COVID-19, and measures taken to mitigate its effects, could result in disruptions to the services provided to the fund by its service providers.

LIBOR risk. The fund’s investments, payment obligations, and financing terms may be based on floating rates, such as the London Interbank Offered Rate, or “LIBOR,” which is the offered rate for short-term Eurodollar deposits between major international banks. Plans are underway to phase out the use of LIBOR by the end of 2021. There remains uncertainty regarding the nature of any replacement rate and the impact of the transition from LIBOR on the fund’s transactions and the financial markets generally. As such, the potential effect of a transition away from LIBOR on the fund or the fund’s investments cannot yet be determined.

Credit risk. An issuer or other obligor (such as a party providing insurance or other credit enhancement) of a security held by the fund or a counterparty to a financial contract with the fund may default or its credit may be downgraded or perceived to be less creditworthy, or the value of assets underlying a security may decline, causing the value of your investment to decline. Changes in actual or perceived creditworthiness may occur quickly. The fund could be delayed or hindered in its enforcement of rights against an issuer, guarantor or counterparty.

Yield risk. The amount of income received by the fund will go up or down depending on variations in short-term interest rates, and when interest rates are very low or negative the fund’s expenses could absorb all or a significant portion of the fund’s income. If interest rates increase, the fund’s yield may not increase proportionately, if for example, the fund’s manager discontinued any temporary voluntary fee limitation or recouped amounts previously waived and/or reimbursed.

Repurchase agreements risk. Repurchase agreements could involve certain risks in the event of default or insolvency of the seller, including losses and possible delays or restrictions upon the fund’s ability to dispose of the underlying securities. To the extent that, in the meantime, the value of the securities that the fund has purchased has decreased, the fund could experience a loss. The use of repurchase agreements may produce income that is not exempt from state personal income tax.

Portfolio management risk. The value of your investment may decrease if the subadviser’s judgment about the quality, relative yield, value or market trends affecting a particular security, industry, sector or region, or about interest rates, is incorrect or does not produce the desired

results, or if there are imperfections, errors or limitations in the tools and data used by the subadviser. In addition, the fund’s investment strategies or policies may change from time to time. Those changes may not lead to the results intended by the subadviser and could have an adverse effect on the value or performance of the fund.

Illiquidity risk. The fund may make investments that are illiquid or that become illiquid after purchase. The liquidity and value of investments can deteriorate rapidly, and they may become difficult or impossible to sell, particularly during times of market turmoil. Illiquid investments may also be difficult to value. Markets may become illiquid when, for instance, there are few, if any, interested buyers or sellers or when dealers are unwilling or unable to make a market for certain securities, including U.S. Treasury securities. During times of market turmoil, there may be few or no buyers or sellers for securities in entire asset classes. If the fund is forced to sell an illiquid investment to meet redemption requests or other cash needs, the fund may be forced to sell at a substantial loss or may not be able to sell at all.

Valuation risk. The sales price the fund could receive for any particular portfolio investment may differ from the fund’s valuation of the investment, particularly for securities that trade in thin or volatile markets or that are valued using a fair value methodology. These differences may increase significantly and affect fund investments more broadly during periods of market volatility. Investors who purchase or redeem fund shares on days when the fund is holding fair-valued securities may receive fewer or more shares or lower or higher redemption proceeds than they would have received if the fund had not fair-valued securities or had used a different valuation methodology. The fund’s ability to value its investments may be impacted by technological issues and/or errors by pricing services or other third party service providers. The valuation of the fund’s investments involves subjective judgment.

Redemption risk. The fund may experience heavy redemptions that could cause the fund to liquidate its assets at inopportune times or at a loss or depressed value and that could affect the fund’s ability to maintain a $1.00 share price. In addition, the fund may suspend redemptions when permitted by applicable regulations.

Cybersecurity risk. Cybersecurity incidents, both intentional and unintentional, may allow an unauthorized party to gain access to fund assets, fund or customer data (including private shareholder information), or proprietary information, cause the fund, the manager, the subadviser and/or their service providers (including, but not limited to, fund accountants, custodians, sub-custodians, transfer agents and financial intermediaries) to suffer data breaches, data corruption or loss of operational functionality or prevent fund investors from purchasing, redeeming or exchanging shares or receiving distributions. A fund, the manager, and the subadviser have limited ability to prevent or mitigate cybersecurity incidents affecting third party service providers, and such third party service providers may have limited indemnification obligations to the fund or the manager. Cybersecurity incidents may result in financial losses to the fund and its shareholders, and substantial costs may be incurred in order to prevent any future cybersecurity incidents. Issuers of securities in which the fund invests are also subject to cybersecurity risks, and the value of these securities could decline if the issuers experience cybersecurity incidents.

These and other risks are discussed in more detail in the Prospectus or in the Statement of Additional Information.

Performance

The accompanying 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 A shares. The table shows the average annual total returns of each class of the fund’s shares that has been in operation for at least one full calendar year. Performance for classes other than those shown may vary from the performance shown to the extent the expenses for those classes differ. The fund makes updated performance information available at www.leggmason.com/moneymarketfunds (select fund and share class), or by calling the fund at 1-877-721-1926 or 1-203-703-6002.

The fund’s past performance is not necessarily an indication of how the fund will perform in the future.

Best Quarter (06/30/2019): 0.46    Worst Quarter (03/31/2015): 0.00

The year-to-date return as of the most recent calendar quarter, which ended 09/30/2020, was 0.21

Management

Investment manager: Legg Mason Partners Fund Advisor, LLC (“LMPFA”)

Subadviser: Western Asset Management Company, LLC

On July 31, 2020, Franklin Resources, Inc. (“Franklin Resources”) acquired Legg Mason, Inc. (“Legg Mason”) in an all-cash transaction. As a result of the transaction, LMPFA and the subadviser(s) became indirect, wholly-owned subsidiaries of Franklin Resources. Under the Investment Company Act of 1940, as amended (the “1940 Act”), consummation of the transaction automatically terminated the management and subadvisory agreements that were in place for the fund prior to the transaction. The fund’s manager and subadviser(s) continue to

provide uninterrupted services with respect to the fund pursuant to new management and subadvisory agreements that were approved by fund shareholders.

Purchase and sale of fund shares

In general, you may purchase, redeem or exchange shares of the fund during fund business hours on any day on which both the New York Stock Exchange and the Federal Reserve Bank of New York are open for business, subject to certain exceptions.

The fund does not impose any minimum initial or subsequent investment requirements with respect to Class N or Service Shares but your Service Agent may. However, if you hold Class A, Class A2 or Class N shares through the fund, you may be subject to a small account fee if the amount in your account does not meet minimum account requirements. See the “Fees and expenses of the fund” section of the Prospectus for more information. “Service Agents” are banks, brokers, dealers, insurance companies, investment advisers, financial consultants or advisers, mutual fund supermarkets and other financial intermediaries that have entered into an agreement with the distributor to sell shares of the fund.

Your Service Agent may impose higher or lower investment minimums, or may impose no minimum investment requirement.

The fund normally calculates its net asset value as of 12:00 noon (Eastern time) and as of the time it closes for business (normally 5:00 p.m. (Eastern time)) on each fund business day. The fund may close early under certain circumstances. For more information, please contact your financial intermediary, or contact the fund by phone (1-877-721-1926 or 1-203-703-6002).

Tax information

The fund’s distributions are generally taxable as ordinary income or capital gains.

Payments to broker/dealers and other financial intermediaries

The fund’s related companies pay Service Agents for the sale of fund shares, shareholder services and other purposes. These payments create a conflict of interest by influencing your Service Agent or its employees or associated persons to recommend the fund over another investment. Ask your financial adviser or salesperson or visit your Service Agent’s or salesperson’s website for more information.

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