Two cash products share almost the same name but are built on different foundations: the money market deposit account offered by a bank, and the money market fund offered by an investment company. This article, which describes United States rules and regulators, explains what separates them and why the difference matters for everyday cash.
Same name, two different legal structures
A money market deposit account (MMDA) is a bank product. Money placed in it is a deposit, a claim on the bank itself, and it sits alongside checking accounts, savings accounts and certificates of deposit (CDs) in the same regulatory category.
A money market fund is something else entirely. It is a type of mutual fund, regulated in the US by the Securities and Exchange Commission (SEC) rather than by bank regulators. Instead of lending your money to a bank, the fund pools cash from many investors and buys short-term, high-quality debt. Investors own shares of the fund, and the fund aims to keep the value of each share steady at $1.00.
The practical consequence is that a deposit account and a fund share are different kinds of asset, even when a brokerage or bank app displays both under a “cash” heading. Which one you hold determines which protections apply.
Which one is covered by FDIC insurance?
According to the Federal Deposit Insurance Corporation (FDIC), deposit insurance protects money in checking, NOW and savings accounts, money market deposit accounts, and time deposits such as CDs. The FDIC states that deposits are insured to at least $250,000 per depositor, per FDIC-insured bank, for each account ownership category.
The same FDIC material lists what is not covered: stocks, bonds and mutual funds, annuities and life insurance policies, municipal securities, crypto assets, and U.S. Treasury bills, bonds and notes. Because a money market fund is a mutual fund, it falls on the uninsured side of that line. Fund documents typically say so plainly, stating that the fund is not insured or guaranteed by the FDIC or any other government agency.
That does not make a money market fund reckless. Funds of this type are designed to hold short-term, liquid, high-quality securities, and the SEC’s rules are meant to reinforce that design. It does mean the protection comes from portfolio rules and regulation rather than from an insurance fund backing the balance. For a deeper look at how the $250,000 figure is applied across ownership categories, see how FDIC deposit insurance ownership categories work.
Can a money market fund lose money?
In principle, yes. A fund aims for a stable $1.00 share price, but that is an objective, not a guarantee. Because the fund owns securities, a sharp fall in the value of those holdings, or heavy withdrawals that force sales at poor prices, can push the value per share below $1.00. Bank deposits do not work this way: the dollar balance of an insured deposit does not fluctuate with market prices.
Not all money market funds carry the same exposure. Broadly, funds that hold only government securities and related repurchase agreements are viewed as the more conservative type, while “prime” funds that also hold corporate short-term debt take on additional credit risk in exchange for a typically higher yield. Tax-exempt funds hold municipal debt. Which category a fund falls into is stated in its prospectus, and it is the first thing worth reading.
How SEC rules changed in 2023
Regulators have tightened the rules for these funds, and the most recent overhaul was adopted by the SEC in July 2023. According to the SEC, the amendments did several things:
- Raised liquidity minimums. The daily liquid asset minimum rose to 25% and the weekly minimum to 50% of fund assets.
- Removed gates. Fund boards can no longer temporarily suspend redemptions when liquidity drops below a threshold.
- Decoupled fees from liquidity levels. The link between a fund’s liquidity level and the imposition of a liquidity fee was removed.
- Added a mandatory liquidity fee for certain funds. Institutional prime and institutional tax-exempt funds must impose a fee when daily net redemptions exceed 5% of net assets, unless the cost of providing liquidity is de minimis.
- Allowed discretionary fees. Any non-government fund must impose a liquidity fee if its board determines doing so is in the fund’s interest.
The SEC’s chair described the sector as “nearly $6 trillion in size” when the rules were adopted, which helps explain the regulatory attention. The mandatory fee rule applies to institutional funds, not to the retail and government funds most households hold, but the underlying principle is the same across the industry: investors who redeem in a stressed moment should bear the cost of the liquidity they use, not those who remain.
What does the difference mean for ordinary savers?
For most households the question is not which product is “better” but which job the money is doing. Three practical differences stand out.
Protection. A deposit at an insured bank is backed by FDIC insurance up to the limits above. A fund share is an investment, and there is no insurance on its value.
Access and mechanics. Deposits are generally available through the bank’s own channels. Fund shares are sold at their net asset value, and the redemption proceeds may take time to settle depending on the platform. Details vary by provider, so the account terms are the authority.
Fees and yield. A fund charges an expense ratio, which is taken out of the fund’s return, while a bank deposit’s advertised rate is the rate. Fund yields move with short-term interest rates, as do deposit rates, but banks can be slower or faster to pass changes through than funds are.
An emergency fund, in particular, is where these differences matter. The core purpose of such money is certainty, which is why cash still plays a distinct role alongside investments, and why building a financial safety net usually starts with deposits that carry explicit insurance.
A worked example of yield, fees and insurance
Illustrative arithmetic helps show why a headline rate is only part of the picture. Assume, purely for illustration, a household holds $20,000 of cash for one year.
| Scenario | Rate or yield | Annual interest |
|---|---|---|
| Bank MMDA | 3.60% | $720 |
| Money market fund, gross | 4.00% | $800 |
| Fund after 0.20% expense ratio | 3.80% | $760 |
Calculations: $20,000 × 0.036 = $720; $20,000 × 0.040 = $800; the 0.20% expense ratio costs $20,000 × 0.002 = $40, leaving $760. In this made-up case the fund still earns $40 more than the deposit, a gap of 0.20 percentage points.
Whether $40 a year is worth giving up FDIC coverage depends on circumstances that are personal, not arithmetic. Note too that the figures are hypothetical: real rates change often, and a published fund yield is usually quoted after expenses. The right way to compare is to use net yields from current disclosures, not marketing headlines.
There is also the question of scale. The $250,000 insured limit applies per depositor, per bank, per ownership category, so a household holding far less than that at one bank is fully inside the protection. Larger balances are where spreading deposits across banks or categories, or choosing government-focused funds, becomes a more relevant consideration.
How to tell what you actually hold
Many people hold a money market product without having chosen it deliberately. A brokerage account’s “sweep” or “core position” may be a fund, a bank deposit program, or plain uninvested cash, depending on the provider. These are not equivalent. Reading the account agreement or the statement’s description will usually reveal which one applies.
A few signals help:
- The word “fund” or a ticker symbol. Fund shares usually have a five-letter ticker and a prospectus.
- FDIC language. Insured deposit products say they are FDIC-insured; funds say they are not.
- A yield figure labeled “7-day.” This is a convention for funds, not for ordinary deposit accounts.
- Who holds the money. A deposit sits at a bank; fund shares sit at a brokerage or fund company.
If the labeling is unclear, the provider’s disclosure documents are the reliable guide. And because savings rates look different once inflation is considered, comparing real, after-fee returns matters more than comparing names.
Choosing by purpose, not by label
The names are similar enough that the products are easy to confuse, but their roles can differ. A money market deposit account is insured, simple and bank-based. A money market fund is a regulated investment that holds short-term debt, often with competitive yields, with no insurance on the share price and with liquidity rules that have been tightened since the 2023 SEC reforms. Neither is inherently superior; the better match depends on what the money is for, how large it is, and how much uncertainty the holder can tolerate.
This article provides general information, not personalized financial advice. Rules, limits and rates change, and this article describes US rules only.
Sources: Federal Deposit Insurance Corporation; U.S. Securities and Exchange Commission
