Morgan Stanley US Government Money Market Trust

05/29/2026 | Press release | Distributed by Public on 05/29/2026 14:21

Summary Prospectus by Investment Company (Form 497K)

Morgan Stanley

U.S. Government Money Market Trust  

Summary Prospectus | May 29, 2026

Share Class and Ticker Symbols

R Class

S Class

DWGXX

DGEXX

Before you invest, you may want to review the Fund's statutory prospectus ("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 Statement of Additional Information ("SAI") and the most recent Annual and Semi-Annual Reports to Shareholders ("Shareholder Reports"), online at www.morganstanley.com/im/USGovernmentMoneyMarketTrust. You can also get this information at no cost by calling toll-free  1-866-414-6349 or by sending an e-mail request to [email protected]. The Fund's Prospectus and SAI, both dated May 29, 2026 (as may be supplemented from time to time), are incorporated by reference into this Summary Prospectus.

Investment Objective

Morgan Stanley U.S. Government Money Market Trust (the "Fund") is a money market fund that seeks to provide security of principal, high current income and liquidity.

Fees and Expenses

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

The Fund is a no-load fund. The Fund does not impose any sales charges and does not charge account or exchange fees. The Fund offers two classes of shares: the R Class and the S Class. Each class has the same fees and expenses.

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

R Class

S Class

Advisory Fee

0.15%

0.15%

Shareholder Servicing Fee

0.10%

0.10%

Other Expenses

0.11%

0.11%

Total Annual Fund Operating Expenses

0.36%

0.36%

Example

The example below is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

DWGSUMPRO 5/26

Morgan Stanley Prospectus | Fund Summary

U.S. Government Money Market Trust  (Con't)

The example below assumes that you invest $10,000 in the Fund, your investment has a 5% return each year and the Fund's operating expenses remain the same. 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

R Class

$ 37

$ 116

$ 202

$ 456

S Class

$ 37

$ 116

$ 202

$ 456

Principal Investment Strategies

The Fund has adopted a policy to invest exclusively in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities, and, accordingly, qualifies as a "government money market fund" under federal regulations. The Fund may also hold cash from time to time. A "government money market fund" is a money market fund that invests at least 99.5% of its total assets in cash, securities issued or guaranteed by the United States or certain U.S. government agencies or instrumentalities and/or repurchase agreements that are collateralized fully by the foregoing. A "government money market fund" is exempt from requirements that permit and, under certain circumstances, require money market funds to impose a "liquidity fee" on redemptions. In selecting investments, Morgan Stanley Investment Management Inc. (the "Adviser") seeks to maintain the Fund's share price at $1.00. The share price remaining stable at $1.00 means that the Fund would preserve the principal value of your investment.

The U.S. government securities that the Fund may purchase include U.S. Treasury bills, notes and bonds, all of which are direct obligations of the U.S. Government. In addition, the Fund may purchase securities issued by agencies or instrumentalities of the U.S. Government which are backed by the full faith and credit of the United States. Among the agencies or instrumentalities issuing these obligations are the Government National Mortgage Association ("Ginnie Mae") and the Federal Housing Administration. The Fund may also purchase securities issued by agencies or instrumentalities which are not backed by the full faith and credit of the United States, but whose issuing agency or instrumentality has the right to borrow, to meet its obligations, from the U.S. Treasury. Among these agencies or instrumentalities are the Federal National Mortgage Association ("Fannie Mae"), the Federal Home Loan Mortgage Corporation ("Freddie Mac") and the Federal Home Loan Banks. Further, the Fund may purchase securities issued by agencies or instrumentalities which are backed solely by the credit of the issuing agency or instrumentality. Among these agencies or instrumentalities is the Federal Farm Credit System. The Fund may also invest in repurchase agreements.

In addition, the Fund has adopted a policy that provides, under normal circumstances, that at least 80% of the Fund's assets will be invested in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities and in repurchase agreements collateralized by such securities. This policy may be changed without shareholder approval; however, shareholders would be notified upon 60 days' notice in writing of any changes.

As a "government money market fund," the Fund may value its securities using the amortized cost method as permitted by Rule 2a-7 under the Investment Company Act of 1940, as amended ("Rule 2a-7" under the "1940 Act"), to seek to maintain a stable net asset value per share of $1.00. The Fund's investments are subject to the quality, diversification, maturity, liquidity and other requirements of Rule 2a-7.

Principal Risks

There is no assurance that the Fund will achieve its investment objective. Investments in the Fund involve risks and you should not rely on the Fund as a complete investment program. The relative significance of each risk factor summarized below may change over time and you should review each risk factor carefully because any one or more of these risks may result in losses to the Fund.

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 ("FDIC") or any other government agency. Morgan Stanley Investment Management Inc. ("MSIM"), 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.

The principal risks of investing in the Fund include:

• Credit and Interest Rate Risk. Credit risk refers to the possibility that the issuer or guarantor of a security, or counterparty to a transaction, will be unable or unwilling or perceived to be unable or unwilling to make interest payments and/or repay the principal on its debt or otherwise honor its obligations, including the risk of default. In such instances, the value of the Fund could decline and the Fund could lose money. If an issuer's, guarantor's or counterparty's financial condition worsens, the credit quality of the issuer, guarantor or counterparty may deteriorate. Credit ratings may not be an accurate

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Morgan Stanley Prospectus | Fund Summary

U.S. Government Money Market Trust (Con't)

assessment of financial condition, liquidity or credit risk. Although credit ratings may not accurately reflect the true credit risk of an instrument, a change in the credit rating of an instrument or an issuer, guarantor or counterparty, or the market's perception of the creditworthiness of an instrument or issuer, guarantor or counterparty can have a rapid, adverse effect on the instrument's value and liquidity and make it more difficult for the Fund to sell at an advantageous price or time. Interest rate risk refers to the decline in the value of a fixed-income security resulting from changes in the general level of interest rates. A wide variety of market and economic factors can cause interest rates to rise or fall, including central bank monetary policy, rising inflation, disinflation or deflation, and changes in general economic conditions. When the general level of interest rates goes up, the prices of most fixed-income securities go down. When the general level of interest rates goes down, the prices of most fixed-income securities go up but the yield or income from new issuances of fixed-income securities generally decreases. Securities with longer durations will generally be more sensitive to changes in interest rates than securities with shorter durations. Fluctuations in interest rates may also affect the liquidity of and income generated by fixed-income instruments held by the Fund.   The Fund may face a heightened level of interest rate risk in times of monetary policy change and/or uncertainty, such as when the Federal Reserve Board adjusts a quantitative easing program and/or changes rates. Changing interest rates may have unpredictable effects on the markets and may detract from Fund performance. A changing interest rate environment increases certain risks, including the potential for periods of market volatility and increased redemptions.  
• Fixed-Income Securities. Fixed-income securities are subject to the risk of the issuer's inability to meet principal and interest payments on its obligations (i.e., credit risk) and are subject to price volatility resulting from, among other things, interest rate sensitivity (i.e., interest rate risk), market perception of the creditworthiness of the issuer and general market liquidity (i.e., market risk). Securities with longer durations are likely to be more sensitive to changes in interest rates, generally making them more volatile than securities with shorter durations. The Fund may be subject to certain liquidity risks that may result from the lack of an active market and the reduced number and capacity of traditional market participants to make a market in fixed-income securities.
• U.S. Government Securities.  Different types of U.S. government securities are subject to different levels of credit risk, including the risk of default, depending on the nature of the particular government support for that security. For example, a U.S. government-sponsored entity, such as Federal National Mortgage Association or Federal Home Loan Mortgage Corporation, although chartered or sponsored by an Act of Congress, may issue securities that are neither insured nor guaranteed by the U.S. Treasury and, therefore, are not backed by the full faith and credit of the United States. With respect to U.S. government securities that are not backed by the full faith and credit of the United States, there is the risk that the U.S. government will not provide financial support to such U.S. government agencies, instrumentalities or sponsored enterprises if it is not obligated to do so by law. U.S. government securities are also subject to interest rate risks and can exhibit price fluctuations resulting from increases or decreases in interest rates.
• Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund's investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund's investments, which may in turn impact the Fund's ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures) adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund's investments, adversely affect the Fund's ability to maintain a stable $1.00 share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund's investments cannot be predicted.
• Repurchase Agreements. Repurchase agreements are subject to risks associated with the possibility of default by the seller at a time when the collateral has declined in value, or insolvency of the seller, which may affect the Fund's right to control the collateral and result in certain costs and delays. Repurchase agreements may involve a greater degree of credit risk than investments in U.S. government securities.
• Large Transactions Risk. The Fund may experience adverse effects when certain large shareholders, or a number of shareholders collectively, purchase or redeem large amounts of shares of the Fund, which may occur rapidly or unexpectedly. Such larger than normal shareholder redemptions may affect the Fund's ability to maintain a stable $1.00 share price and negatively impact the Fund's liquidity. In some circumstances, the Fund may hold a relatively large proportion of its assets in cash in anticipation of large redemptions. These large redemptions may also force the Fund to sell portfolio securities or other assets when it might not otherwise do so, which may affect the Fund's ability to maintain a

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Morgan Stanley Prospectus | Fund Summary

U.S. Government Money Market Trust  (Con't)

stable $1.00 share price and increase the Fund's transaction costs. In addition, large purchases of Fund shares may adversely affect the 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.
• Stable NAV Risk. The Fund may not be able to maintain a stable $1.00 share price at all times. If the Fund or another money market fund fails to maintain a stable NAV  (or if there is a perceived threat of the inability to maintain a stable NAV), the Fund could be subject to increased redemptions, which may adversely impact the Fund's ability to maintain a stable $1.00 share price.
• Active Management Risk. In pursuing the Fund's investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund's performance.

Please see "Additional Information About Fund Investment Strategies and Related Risks" in the Fund's prospectus for a more detailed description of risks of investing in the Fund. Shares of the Fund are not bank deposits and are not guaranteed or insured by the FDIC or any other government agency.

Past Performance

The bar chart and table below provide some indication of the risks of investing in the Fund by showing changes in the performance of the Fund's R Class shares from year-to-year and by showing the Fund's average annual returns for the past one, five and 10 year periods and since inception. The Fund's past performance is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available online at www.morganstanley.com/im or by calling toll-free 1-800-869-6397.

Annual Total Returns-Calendar Years

The year-to-date total return as of  March 31, 2026 was 0.84%.

During the periods shown in the bar chart above:

High Quarter

12/31/23

1.28%

Low Quarter

03/31/22

0.00%

Average Annual Total Returns  

(for the calendar periods ended December 31, 2025)    

Past 1 Year

Past 5 Years

Past 10 Years

Since Inception*

R Class

4.00%

3.01%

1.92%

3.40%*

S Class

4.00%

3.02%

N/A

2.02%*

* R Class commenced operations on February 17, 1982 and S Class commenced operations on June 28, 2016.

For the Fund's most recent 7-day annualized yield, you may call toll-free 1-800-869-6397.

Fund Management

Adviser. Morgan Stanley Investment Management Inc.

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Morgan Stanley Prospectus | Fund Summary

U.S. Government Money Market Trust (Con't)

Purchase and Sale of Fund Shares

The minimum initial investment is generally $1,000 for shares of the Fund and the minimum subsequent investment is generally $50. The minimum investment requirement may be waived for certain investments. For more information, please refer to the section of the Prospectus entitled "Shareholder Information-How to Buy Shares-Minimum Investment Amounts."

You can purchase or sell Fund shares on any day the New York Stock Exchange ("NYSE") is open for business (except when the following federal holidays are observed: Columbus Day and Veterans Day) by contacting your Morgan Stanley Financial Advisor or other authorized third-party, such as a broker-dealer or other financial intermediary that has entered into a selling agreement with the Fund's "Distributor," Morgan Stanley Distribution, Inc. (each, a "Financial Intermediary"). In addition, you can sell Fund shares at any time through the check-writing option (with respect to R Class shares only) or by enrolling in a systematic withdrawal plan. Your shares will be sold at the next price calculated after we receive your order to redeem. For more information, please refer to the sections of the Prospectus entitled "Shareholder Information-How to Buy Shares" and "-How to Sell Shares."

Tax Information

The Fund intends to make dividends and distributions that may be taxed as ordinary income or capital gains, unless you are investing through a tax-deferred arrangement, such as a 401(k) plan or an individual retirement account ("IRA").

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase Fund shares through a Financial Intermediary (such as a bank), the Adviser and/or the Distributor may pay the Financial Intermediary for the sale of Fund shares and related services. These payments, which may be significant in amount, may create a conflict of interest by influencing the Financial Intermediary and your salesperson to recommend the Fund over another investment. Ask your salesperson or visit your Financial Intermediary's web site for more information.

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© 2026 Morgan Stanley

DWGSUMPRO 5/26

Morgan Stanley US Government Money Market Trust published this content on May 29, 2026, and is solely responsible for the information contained herein. Distributed via EDGAR on May 29, 2026 at 20:21 UTC. If you believe the information included in the content is inaccurate or outdated and requires editing or removal, please contact us at [email protected]