Money market funds are among the safest investments available, but they are not risk-free, and whether money market funds are safe for your money depends on which of the three types you hold. Government funds, which hold the bulk of the roughly $7.8 trillion invested in the category, have never caused investor losses. Prime and tax-exempt funds carry more credit and liquidity risk, and their institutional share classes now operate under rules that can charge you a fee to redeem during a crisis. None of these funds are FDIC-insured, which is the point most savers get wrong.
What Makes These Funds Safe in the First Place
A money market fund is a mutual fund that invests only in short-term, high-quality debt: U.S. Treasury bills, government agency debt, commercial paper from large corporations, bank certificates of deposit, and repurchase agreements. The goal is capital preservation. You put a dollar in, you get a dollar back, plus interest.
Short maturities do most of the work. When a fund holds debt that matures in days or weeks, there is very little time for the issuer’s finances to deteriorate. If rates shift or a borrower weakens, the fund lets the security mature and reinvests in something better. That constant turnover is why these funds behave like cash even though they are technically investments.
SEC Rule 2a-7 sets the guardrails. No individual security can have more than 397 days to maturity, and the fund’s weighted average maturity cannot exceed 60 days. Every fund must keep at least 25% of its assets in securities that convert to cash within one business day, and at least 50% in securities that convert to cash within five business days. Those daily and weekly liquid asset floors were raised from 10% and 30% under the SEC’s 2023 reform package.1U.S. Securities and Exchange Commission. Money Market Fund Reforms
The Safety Difference Between the Three Types
The categories share the same regulatory framework, but the risk they take within it varies enough that the wrong choice can expose you to problems you did not expect.
Government Funds Are the Safest
Government funds invest almost entirely in U.S. Treasury securities, government agency debt, and repurchase agreements backed by those instruments. No government money market fund has ever broken the buck. During both the 2008 financial crisis and the March 2020 market panic, these funds received massive inflows as investors fled riskier options. If safety is your priority and you can accept a slightly lower yield, this is where most of the category’s $7.8 trillion sits for a reason.
Prime Funds Take Real Credit Risk
Prime funds hold corporate commercial paper, bank certificates of deposit, and other private-sector debt alongside government securities. The extra credit risk usually produces yields 15 to 30 basis points higher than government funds. It also produced the two worst episodes in the category’s history. Prime funds saw severe redemption pressure in both 2008 and 2020.
Structure matters here. Institutional prime funds are required to use a floating net asset value, meaning the share price moves to four decimal places rather than staying pinned at $1.00. Retail prime funds, limited to individual investors, still maintain a stable $1.00 NAV. If you invest through an employer cash management program or a corporate treasury account, you are likely in an institutional fund and exposed to that floating price.
Tax-Exempt Funds Carry Municipal and Liquidity Risk
Tax-exempt funds hold short-term municipal securities issued by state and local governments. Municipal issuers default far less often than corporations, but the market for short-term municipal debt is thinner than the Treasury or commercial paper markets, and that thinness can create liquidity problems in a crisis. Institutional tax-exempt funds, like institutional prime funds, use a floating NAV and are subject to the mandatory liquidity fee framework described below.
The Two Times a Fund Broke the Buck
In the entire history of the category, only two money market funds have ever broken the buck, meaning their share price fell below $1.00. The first was the Community Bankers U.S. Government Money Market Fund in 1994, a small fund that caused little broader disruption. The second is the defining cautionary tale for the industry: the Reserve Primary Fund in September 2008.
The Reserve Primary Fund held $785 million in Lehman Brothers commercial paper when Lehman filed for bankruptcy on September 15, 2008. The next day, the fund marked its Lehman holdings to zero, and the NAV dropped to $0.97 per share. Investors rushed to redeem, the fund froze withdrawals above $10,000, and a full liquidation began within two weeks. Investors recovered about 79 cents on the dollar by December 2008. The final distribution did not arrive until December 2014, when total recoveries reached 99.1 cents per share. Waiting six years to get nearly all your cash back is the nightmare scenario every subsequent rule has tried to prevent.
The fallout was worse than the fund itself. Within two days of the Reserve Primary Fund’s collapse, investors pulled more than $300 billion from prime money market funds across the industry. The Treasury Department stepped in with a temporary guarantee program, and the Federal Reserve created emergency lending facilities to stabilize the commercial paper market. Money market funds, despite their cash-like appearance, can transmit panic through the financial system.
What the 2023 SEC Reforms Changed
The SEC adopted major amendments to Rule 2a-7 in July 2023, largely in response to the March 2020 disruption when institutional prime and tax-exempt funds again experienced destabilizing redemption surges.2U.S. Securities and Exchange Commission. SEC Adopts Money Market Fund Reforms and Amendments to Form PF Reporting Requirements for Large Liquidity Fund Advisers Two changes matter for your safety analysis.
Redemption gates are gone. Under the old rules, a fund’s board could temporarily block you from withdrawing your money if weekly liquid assets dropped below 30%. The SEC concluded that this power actually made crises worse, because investors raced to redeem before a gate could be imposed. The new rules eliminate gates entirely.1U.S. Securities and Exchange Commission. Money Market Fund Reforms
Mandatory liquidity fees replaced them. Institutional prime and institutional tax-exempt funds must now impose a liquidity fee when daily net redemptions exceed 5% of the fund’s net assets, unless the liquidity cost is negligible. The board of any non-government money market fund can also impose a discretionary liquidity fee when it determines that doing so is in the fund’s best interest.2U.S. Securities and Exchange Commission. SEC Adopts Money Market Fund Reforms and Amendments to Form PF Reporting Requirements for Large Liquidity Fund Advisers The idea is that investors pulling money out during a liquidity crunch should bear the cost of that withdrawal rather than pass it to the investors who stay.
Funds must also publish detailed portfolio information on their websites. Daily disclosures include the percentage of assets in daily and weekly liquid assets, net inflows and outflows, and the fund’s NAV per share. Monthly disclosures include a full schedule of holdings with issuer names, maturity dates, and values.3U.S. Securities and Exchange Commission. ADI 2025-15 – Website Posting Requirements You can check your fund’s actual risk exposure on any business day.
These Are Not Bank Accounts
The most common confusion is treating a money market fund like a bank savings account. They look similar on a brokerage statement, they pay comparable interest, and you can usually access the money within a day. The legal protections are completely different.
Bank savings accounts and CDs are insured by the FDIC up to $250,000 per depositor, per bank, per ownership category.4FDIC.gov. Understanding Deposit Insurance If the bank fails, the FDIC pays you back. That coverage extends to losses from any cause, including terrible lending decisions by the bank.
Money market fund shares are not FDIC-insured. They are covered by SIPC, but only against the failure of your brokerage firm, not against a decline in the fund’s value. SIPC protection covers up to $500,000 in securities and cash, with a $250,000 sublimit for cash.5Securities Investor Protection Corporation (SIPC). What SIPC Protects If your brokerage goes bankrupt and your money market fund shares go missing from your account, SIPC steps in. If the fund itself loses value, SIPC does nothing. That distinction is the whole ballgame for a saver deciding between the two.
If you need every dollar guaranteed and do not need more than $250,000 in coverage, a high-yield savings account gives you similar returns with FDIC insurance. Money market funds become more attractive when you are parking larger sums, staying within a brokerage account for easy reallocation, or want the state tax advantages of a government fund holding Treasury securities.
How to Check Whether Your Own Fund Is Safe
Knowing the categories is not enough. Within each category, individual funds vary in credit quality and liquidity. A few things to actually check before deciding your money is where it should be:
- Fund type. Confirm whether the fund is government, prime, or tax-exempt. If safety is your top priority and you are not chasing every basis point, government funds are the straightforward choice.
- Institutional vs. retail share class. If you are investing as an individual, confirm you are in a retail share class. Institutional funds carry the floating NAV and mandatory liquidity fee provisions that make them less cash-like.
- Weekly liquid assets. Look at the fund’s daily website disclosure. The SEC minimum is 50%, but many well-run funds hold 60% or higher. A fund running consistently near the floor is tighter than it needs to be.
- Portfolio holdings. The monthly disclosure lists every security by issuer and maturity. If a prime fund is concentrated in issuers you would not lend to yourself, that is information you can act on.
The SEC also requires monthly filings on Form N-MFP that provide a complete breakdown of every security the fund holds.3U.S. Securities and Exchange Commission. ADI 2025-15 – Website Posting Requirements If a fund makes this data hard to find, that itself is a signal about how the sponsor thinks about transparency.