SUPPLEMENT DATED MARCH 26, 2020 TO THE PROSPECTUS OF

Morgan Stanley California Tax-Free Daily Income Trust, dated April 30, 2019
Morgan Stanley New York Municipal Money Market Trust, dated April 30, 2019
Morgan Stanley Tax-Free Daily Income Trust, dated April 30, 2019
Morgan Stanley U.S. Government Money Market Trust, dated May 31, 2019
Morgan Stanley U.S. Government Securities Trust, dated April 30, 2019

The following is hereby added at the end of the section of the Prospectus entitled "Fund Summary—Principal Risks":

Market and Geopolitical Risk. The value of your investment in the Fund is based on the market prices and values of the Fund's investments, which change daily due to economic and other events that affect markets generally, as well as those that affect particular regions, countries, industries, companies or governments. These events may be sudden and unexpected, and could adversely affect the value and liquidity of the Fund's investments, which may in turn impact a 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 natural disasters, epidemics and pandemics, terrorism, conflicts and social unrest) adversely interrupt the global economy and financial markets. It is difficult to predict when events affecting the U.S. or global financial markets may occur, the effects that such events may have and the duration of those effects (which may last for extended periods).

The following is hereby added immediately after the section of the Prospectus entitled "Fund Details—Additional Information about the Fund's Investment Objective, Strategies and Risks—Additional Information About the Fund's Investment Strategies and Principal Risks":

Market and Geopolitical Risk

The value of your investment in the Fund is based on the market prices of the securities the Fund holds. These prices change daily due to economic and other events that affect markets generally, as well as those that affect particular regions, countries, industries, companies or governments. These price movements, sometimes called volatility, may be greater or less depending on the types of securities the Fund owns and the markets in which the securities trade. Volatility and disruption in financial markets and economies may be sudden and unexpected, expose the Fund to greater risk, including risks associated with reduced market liquidity and fair valuation, and adversely affect the Fund's operations. For example, the Adviser potentially will be prevented from executing investment decisions at an advantageous time or price as a result of any domestic or global market disruptions and reduced market liquidity may impact the Fund's ability to sell securities to meet redemptions.

The increasing interconnectivity between global economies and financial markets increases the likelihood that events or conditions in one region or financial market may adversely impact issuers in a different country, region or financial market. Securities in the Fund's portfolio may underperform due to inflation (or expectations for inflation), interest rates, global demand for particular products or resources, natural disasters, health emergencies (such as epidemics and pandemics), terrorism, regulatory events and governmental or quasi-governmental actions. The occurrence of global events similar to those in recent years, such as terrorist attacks around the world, natural disasters, health emergencies, social and political discord or debt crises and downgrades, among others, may result in market volatility and may have long term effects on both the U.S. and global financial markets. Other financial, economic and other global market and social developments or disruptions may result in similar adverse circumstances, and it is difficult to predict when similar events affecting the U.S. or global financial markets may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). In general, the securities or other instruments that the Adviser believes represent an attractive investment opportunity or in which the Fund seeks to invest may be unavailable entirely or in the specific quantities sought by the Fund. As a result, the Fund may need to obtain the desired exposure through a less advantageous investment, forgo the investment at the time or seek to replicate the desired exposure through a derivative transaction or investment in another investment vehicle. Any such