Money Market Funds: Safe Cash Management for Investors
Money market funds invest in short-term, high-quality debt like Treasury bills, commercial paper, and repurchase agreements. They aim to maintain a stable $1.00 NAV while providing higher yields than bank savings accounts, with check-writing and instant liquidity.
Money market funds were created in the 1970s and quickly became a popular alternative to bank savings accounts because they offered higher yields and check-writing privileges. They are regulated under Rule 2a-7 of the Investment Company Act, which imposes strict requirements: weighted average maturity must be 60 days or less, no more than 5% of assets can be in any single issuer (except government securities), and credit quality must be the highest (rated AAA, Aaa, or equivalent). These rules make money market funds among the safest investments available, though they are not FDIC-insured.
As of 2024, Vanguard Federal Money Market Fund (VMFXX) yielded about 5.3%, Vanguard Municipal Money Market Fund (VMSXX) yielded about 3.2% (tax-equivalent yield of 5.3%+ for high earners), and the average bank savings account yielded 0.5%. The difference is substantial — a $100,000 balance in VMFXX earning 5.3% generates $5,300 per year versus $500 in a typical savings account. Money market funds are available as the settlement fund in most brokerage accounts, meaning your uninvested cash automatically earns money market yields.
Real-world example: In 2023, when the Federal Reserve raised interest rates to 5.25% to 5.50%, money market funds saw record inflows exceeding $1 trillion as investors moved cash from bank accounts paying 0.5% to money market funds paying 5%+. The Vanguard Federal Money Market Fund (VMFXX) became the fastest-growing fund in history, surpassing $300 billion in assets. Investors who kept their emergency funds in bank savings accounts lost 4% to 5% in forgone yield compared to money market fund investors.
Types of Money Market Funds
Government money market funds (like VMFXX, FZFXX) invest in US Treasury bills, agency securities, and repurchase agreements backed by government collateral. They are the safest type and had zero losses during the 2008 financial crisis. Prime money market funds invest in corporate commercial paper, certificates of deposit, and other short-term corporate debt. They offer slightly higher yields than government funds but carry marginally more risk — one prime fund "broke the buck" (fell below $1.00 NAV) in 2008. Municipal money market funds invest in short-term municipal securities. Their interest is exempt from federal income tax and sometimes state tax, making them ideal for high-income investors in taxable accounts. Tax-exempt money market funds typically yield 60% to 80% of taxable money market funds, which is advantageous for investors in the 35%+ tax bracket. Treasury-only money market funds invest exclusively in US Treasury bills — the safest of all — and are popular for investors who want zero credit risk.
FAQs
Are money market funds FDIC insured?
No. Money market funds are not FDIC insured. They are investment products, not bank deposits. However, government money market funds that invest exclusively in US Treasury securities are backed by the full faith and credit of the US government, making them extremely safe. The risk of a government money market fund losing money is considered negligible. The 2008 financial crisis was the only time a money market fund "broke the buck" (the Reserve Primary Fund, a prime fund that held Lehman Brothers commercial paper). Since then, regulations have been strengthened to prevent this.
What is the difference between a money market fund and a money market account?
A money market fund is an investment product regulated by the SEC. A money market account (MMA) is a bank deposit account regulated by the FDIC and insured up to $250,000 per depositor. Money market funds typically offer higher yields than money market accounts because they take slightly more credit risk and have lower operating expenses. Money market accounts may limit withdrawals to six per month, while money market funds generally have no withdrawal limits and may offer check-writing.
How are money market fund dividends taxed?
Dividends from government and prime money market funds are taxed as ordinary income at your marginal tax rate. Municipal money market fund dividends are exempt from federal income tax. If the fund holds only securities from your state of residence, the dividends may also be exempt from state and local income taxes. For high-income investors in states with high income taxes (California, New York, New Jersey), in-state municipal money market funds can provide significant tax savings. Always compare after-tax yields when choosing between taxable and tax-exempt money market funds.