Money-Market Account vs Money-Market Fund: Key Differences

*A money-market account is a bank savings product offering FDIC insurance up to $250,000, while a money-market fund is an SEC-regulated mutual fund holding short-term debt securities with no insurance. The account has slower interest-rate adjustments; the fund offers better yields but no principal guarantee. Neither is a checking account, though both allow limited transfers.

What Is a Money-Market Account?

A money-market account (MMA) is a deposit product offered by a bank or credit union. It is essentially a hybrid between a savings account and a checking account: you earn interest (typically higher than a plain savings account), you can write checks (usually limited), and you can make electronic transfers (also limited). The key feature: the account is a bank deposit, not an investment. Your principal is insured by the Federal Deposit Insurance Corporation (FDIC) up to $250,000 per depositor, per bank, per category.

Because an MMA is a deposit, not a security, it is regulated by the Office of the Comptroller of the Currency (OCC) or the state banking authority, not the Securities and Exchange Commission. The bank holds your deposit and invests it in its own portfolio—loans, securities, etc.—keeping the difference between what it pays you and what it earns.

Interest rates on MMAs are variable and set by the bank at its discretion. Banks typically reprice every month or quarter, but they are not obligated to pass along rate changes immediately. During periods of rising rates, banks have been notoriously slow to raise MMA rates; during falling-rate environments, they often cut rates faster than the Federal Reserve cuts the federal funds rate. This lag is a known drag on MMA returns.

What Is a Money-Market Fund?

A money-market fund is a mutual fund that invests exclusively in short-term debt securities: Treasury bills, commercial paper, repurchase agreements, and other instruments maturing in 270 days or less. It is regulated as an open-end fund by the SEC under the Investment Company Act of 1940.

A money-market fund issues shares to investors and holds those proceeds in short-term securities. As securities mature or new ones are purchased, the fund’s portfolio turns over frequently—daily, in many cases. The fund pays no insurance; if it invests in commercial paper from a company that defaults, the fund and its shareholders absorb the loss.

Until 2023, money-market funds were required to maintain a constant net asset value (NAV) of $1.00 per share, meaning their price never moved, only the interest distribution did. The SEC relaxed this rule in late 2022, allowing new “municipal” and “institutional” funds to use floating NAVs (where the share price moves with the market value of the portfolio). Most retail money-market funds still maintain the $1.00 NAV to feel like a bank product, but the flexibility is now available.

Yield Differences

Money-market funds typically offer higher yields than money-market accounts, especially during periods when the federal funds rate is high or when the yield curve is steep. This is because:

1. Competitive pressure: Money-market funds compete openly on yield; banks have less competitive pressure because depositors value FDIC insurance.
2. No intermediary markup: A money-market fund passes through the yield of its holdings minus a small expense ratio (often 0.1–0.5%). A bank account pays you a spread between what the bank earns and what it pays you.
3. Rate transmission: Money-market funds adjust daily; MMAs adjust slowly and selectively.

In practice, a money-market fund yielding 5.0% annually while a money-market account yields 4.2% is not unusual when both markets are actively competing. The 80 basis-point spread is the difference between the fund’s direct pass-through and the bank’s middleman markup.

Insurance and Safety

An MMA is insured up to $250,000 by the FDIC. You are depositing with a bank, and the FDIC covers deposits if the bank fails. (In real terms, a major U.S. bank failure is extremely rare, and the FDIC has a track record of making depositors whole.)

A money-market fund is not insured. If the fund invests in commercial paper from a company that defaults, the fund’s NAV falls and shareholders take the loss. The fund manager may have portfolio quality rules (e.g., “no paper below A-1 rated”), which reduce default risk, but the risk is not zero.

However, historically, money-market fund defaults have been vanishingly rare. The only notable systemic event was the 2008 financial crisis, when the Reserve Primary Fund “broke the buck” (fell below $1.00 NAV) after holding Lehman Brothers debt. The Federal Reserve later provided emergency support to stabilize money-market funds. Outside of that extreme scenario, money-market funds have been reliable.

Accessibility and Transactions

An MMA allows limited deposits, withdrawals, and checks. Federal Regulation D historically capped electronic transfers at 6 per month (this limit was suspended in 2020 but remains on the books). You can usually write a limited number of checks directly from the account, though some banks restrict this feature.

A money-market fund does not allow checks, but you can buy and sell shares freely. If you hold the fund in a brokerage account, you can also request redemptions into your linked checking account, effectively giving you access to your cash in one business day.

For everyday spending, neither is a checking account, and neither is meant to be. MMAs are for people who want interest on savings plus occasional check-writing; money-market funds are for investors who want the best available yield on cash reserves.

Tax Considerations

Interest on an MMA is ordinary income taxed at your marginal federal rate, and also subject to state and local tax. Interest on a money-market fund holding Treasury bills is ordinary income federally but exempt from state tax. If the fund holds commercial paper or other non-Treasury debt, all interest is subject to both federal and state tax. So a Treasury-focused money-market fund can be tax-advantaged in high-tax states compared to an MMA.

Which Should You Choose?

Choose a money-market account if:

• You value principal safety and insurance over yield.
• You want limited check-writing or debit-card access.
• You are in a lower tax bracket and do not benefit from state-tax exemptions.
• You prefer a simple, single-institution product.

Choose a money-market fund if:

• You want the highest available yield on cash.
• You live in a high-tax state and the fund holds Treasury bills (for state-tax exemption).
• You are comfortable with minimal credit risk.
• You want to hold your cash alongside other investments in a brokerage account.

Both are legitimate “safety buckets” for short-term reserves, and neither should be used for money you need immediate access to without any volatility risk—that is what a traditional savings account is for.

See also