Government money market mutual funds include funds that only invest in the following assets:

  • U.S. Treasury securities
  • Repurchase agreements collateralized by U.S. Treasury securities
  • Other types of government securities

Government money market funds attract conservative investors who gravitate to stable, highly liquid vehicles that carry minimal credit risk. Consequently, nearly all mutual fund providers offer some version of these funds. The following three well-known examples dominate the investment landscape and have helped popularize this investment category. 

Key Takeaways

  • Government money market mutual funds include funds that only invest in U.S. Treasury securities and repurchase agreements collateralized by U.S. Treasury securities.
  • Government money market funds attract conservative investors because they are stable, highly liquid vehicles with minimal credit risk.
  • Three top money market mutual funds are the Fidelity Government Money Market Fund (SPAXX), the Vanguard Federal Money Market Fund (VMFXX), and the American Century Capital Preservation Fund (CPFXX).

Fidelity Government Money Market Fund (SPAXX) 

Fidelity launched the Fidelity Government Money Market Fund (SPAXX) in 1990, and boasts $219.95 billion in total assets as of May 2021, making it one of the most widely held funds in this category. Similar to the American Century Capital Preservation Fund, SPAXX strives to usher in high-yield returns, with high liquidity, and an emphasis on capital preservation.

The fund is typically 99.5% or more invested in cash or cash equivalents in the form of short-term U.S. government securities or repurchase agreements that are fully collateralized by cash or such securities. Some U.S. government securities are issued by duly authorized government agencies but are not directly issued nor guaranteed by the U.S. Treasury.

In selecting the fund's investments, the fund’s management team focuses on maintaining a stable $1 net asset value (NAV) share price. The weighted average maturity of the portfolio holdings is 54 days.

As of May 2021, the fund’s top holdings included the following:

  • U.S. Treasury Bills (24.28%)
  • U.S. Government Repurchase Agreements (49.75%)
  • Agency Floating-Rate Securities (11.57%)
  • Agency Fixed-Rate Securities (7.62%)
  • U.S. Treasury Coupons (6.31%)

The fund has an annual expense ratio of 0.42% and a dividend yield of 0.01%. Its one-year total return is 0.00%. This fund is well suited for investors who prefer its broad range of investments.

Vanguard Federal Money Market Fund (VMFXX)

Vanguard launched the Vanguard Federal Money Market Fund (VMFXX) in 1981. Total AUM as of May 2021 is $193.8 billion. This fund has the same investment aims of providing capital preservation and current income through investing in high-quality, short-term U.S. government securities.

Vanguard bills this fund as one of the most conservative offerings in this category, making it an ideal choice for conservative seeking risk avoidance and capital preservation.

As of May 2021, the fund’s top allocation was to U.S. Treasury Bills at 75.4%, followed by U.S. Government Obligations at 23.6% and Repurchase Agreements at 1.0%. The average maturity of the portfolio holdings was 55 days. The expense ratio for the Vanguard Federal Money Market Fund is 0.11%; the dividend yield is 0.02%, and the one-year total return is 0.45%.

American Century Capital Preservation Fund (CPFXX)

The American Century Investments Capital Preservation Fund Investor Class (CPFXX) was launched by American Century in 1972, and has over $2.22 billion in total assets under management (AUM), as of June 2021. The fund is primarily known for maximizing safety and liquidity. The fund aims to achieve the highest possible yield return consistent with its asset mix, which consists of Treasury bills, bonds, and notes. The fund ordinarily invests solely in short-term U.S. Treasury money market securities. The weighted average maturity of its portfolio holdings is 58.55 days.

The gross annual expense ratio for the Capital Preservation Fund was 0.48% as of May 2021. Its one-year total return as of December 2020 was 0.01%. This mutual fund is appropriate for investors whose current investment goals align with those of the strategy and who seek a pure-play government money market fund that invests exclusively in U.S. Treasury securities.

Special Considerations

Money market mutual funds can be perfect vehicles for risk-averse investors. Barring a financial crisis, there is little risk associated with these vehicles. Furthermore, some money market accounts and funds come with withdrawal or check writing features, making them a viable alternative to standard checking and savings accounts for some investors.