Are Money Market Funds Insured? The Reserve Fund Broke the Buck
No. Money market funds are not insured. No federal agency stands behind a share the way the FDIC stands behind a bank deposit. A share is worth whatever the fund's holdings are worth, and the steady one-dollar price is a target the manager works to hold, not a promise anyone outside the fund has underwritten.
The confusion is understandable, because the words collide. A bank account with "money market" in its name is a deposit and is insured. A money market fund is a mutual fund — shares in a pool of short-term IOUs. On September 16, 2008, the day after Lehman Brothers filed for bankruptcy, the Reserve Primary Fund broke the dollar. It held roughly $785 million of Lehman CP and medium-term notes1 — short-term IOUs issued by the bank. One percent was enough. Holders who had treated the fund as a checking account with a better rate found redemptions halted and their money returned in installments over the months that followed.
A later crisis put the same question to deposits instead. When a major bank failed, the balances at risk were ordinary deposits above the insurance limit, covered in the end by an emergency decision rather than by any standing rule.
Both episodes turn on a question rarely asked the week a wire lands: who, exactly, stands behind this dollar? The table sets out the common resting places for sale proceeds — compared by structure, not by rate.
Who Stands Behind the Dollar: Deposits, Sweeps, Funds and Bills
| Where the cash sits | What it legally is | Who stands behind the dollar | Insured? | The question to ask |
|---|---|---|---|---|
| Bank deposit, including an account called a money market account | A loan to one bank, repayable on demand | The bank's balance sheet, then the FDIC to the statutory limit | Yes, to the statutory limit per depositor, per bank, per ownership category | How much sits above the limit, at how many banks? |
| Deposit-placement network (one relationship, cash spread across many banks) | Separate deposits at many banks | Each receiving bank, to its own limit — not the network | Yes, only if each placement sits inside a limit | Is every dollar at a distinct insured bank, in writing? |
| Brokerage cash sweep | A bank deposit or fund shares; the program can switch | Whatever the sweep lands in that week | Only when it lands in a bank deposit, and only to the limit | What is the vehicle today, and can the firm change it? |
| Government money market fund | Shares in a fund of Treasury and agency paper, often with repos | The fund's holdings | No | Treasuries only, or agency debt and repos as well? |
| Prime money market fund | Shares in a fund of short-term corporate and bank debt | The issuers of that paper | No; institutional shares do not even target a fixed dollar | Who are the largest issuers, and can withdrawals be met in a run? |
| Treasury bills held directly | A direct short-term obligation of the U.S. government | The U.S. Treasury | Not insured; nothing stands between holder and issuer | Held in whose name, with which custodian? |
When This Table Is Wrong
It is wrong whenever the label on the statement is trusted over the document behind it. "Cash" at a brokerage is not a legal category: many sweep programs reserve the right to move a balance from a bank deposit into a fund without a fresh decision from the client. Broker-level protection covers assets that go missing if the firm itself fails; it does not cover a fall in the value of a fund.
It is wrong on size. Deposit insurance was built around households, not sale proceeds. Above the limit, the holder is simply an unsecured lender to one institution, however the statement is formatted. Ownership categories — joint accounts, trusts, entities — stretch coverage, but only with deliberate structuring and only so far. Covering uninsured balances in a crisis was an exception granted under emergency authority, not a rule to plan around.
It is wrong on the word government. A fund carrying "U.S. Government" in its name can still hold agency paper and derivatives tied to agency securities rather than plain Treasury bills — and that distinction has mattered to shareholders in past episodes. Agency paper and repurchase agreements are not a Treasury bill held to maturity in the owner's name.
And it understates the risk that actually bit in 2008: access. Reserve Primary's holders did not lose three cents and move on; they lost the use of the money for months. Current rules have been revised to address liquidity stress at institutional prime and tax-exempt funds, including mandatory liquidity fees under certain conditions. A fee is not a lockup — but a lockup can still arrive when the underlying paper cannot be sold, which is precisely what 2008 was. A sponsor's voluntary support of the one-dollar price, even when the prospectus mentions it, is not insurance.
The Checklist Before Anyone Mentions a Rate
The table is an agenda, not a ranking. For every dollar of proceeds: which row it sits in, who stands behind it, whether that backing has a cap, and what it takes to get the money back on a bad day. These belong with the other questions worth putting to a manager — asked before the conversation turns to what the cash is earning, because the owners who had quiet weeks in 2008 and 2023 already knew the answers.
Sources
Figures marked with a superscript were checked against these sources on October 14, 2026.
- Reserve failed money fund finally sells Lehman debt reuters.com — $785 million of Lehman CP and medium-term notes