Two products in American banking share the phrase money market, and the similarity ends at the name. One is a deposit and the other is an investment fund.
A deposit account is a bank liability
A money market deposit account is held at a bank or credit union, and the balance is an obligation of that institution to the depositor.
The institution uses deposits to fund lending and pays a rate it sets, which it can change at its discretion.
Because it is a deposit, it falls within federal deposit insurance coverage subject to the applicable limits and ownership rules.
A money market fund is a portfolio
A money market fund is a mutual fund that holds short-term debt instruments such as Treasury bills and other short-dated obligations.
The investor owns shares in the fund rather than a claim on any institution, and the yield reflects what the underlying holdings earn less the fund's expenses.
Deposit insurance does not apply to fund shares, because nothing about the arrangement involves a bank holding a deposit.
Different protections apply to each
Brokerage accounts carry protection that addresses the failure of the brokerage firm and the custody of assets, which is a different risk from investment loss.
No protection scheme covers a decline in the value of the underlying holdings, in either a fund or any other investment.
Money market funds are governed by rules that constrain the maturity and credit quality of what they can hold, which is a structural safeguard rather than a guarantee.
Yields move on different clocks
A fund's yield tracks the short-term instruments it holds, so it reprices as those instruments mature and are replaced at current rates.
A bank sets a deposit rate as a business decision, weighing competitive pressure and its own funding needs, so it can lag market movements in either direction.
That difference is why the two products can pay noticeably different rates at the same moment despite serving a similar purpose.
Access works differently too
Deposit accounts typically offer immediate access through a debit card, transfers or checks, with the institution's own limits applied.
Fund shares settle on a schedule, so moving money out involves a redemption and a transfer rather than an instant withdrawal.
Neither arrangement is superior in the abstract. They differ in what the balance actually is, and that distinction determines everything else about the product.