Money Market Funds Breaking the Buck: What a Drop Below $1 NAV Means

You parked $80,000 in a money market fund because you needed it in four months for a house closing, and the account has shown $1.00 a share every single day you’ve looked at it. Breaking the buck means that number prints as $0.99 or lower, and your $80,000 becomes $79,200. The loss itself is usually small. The part that actually hurts is that the same conditions that push the price below a dollar are the conditions under which the fund can slow down or charge you for getting your cash out, so the money you needed on Friday isn’t there on Friday.

Key points

• A stable $1.00 share price is an accounting convention, not a guarantee: the fund rounds its true per-share value to the nearest cent, so it can absorb losses up to half a cent per share before the printed price moves.
• On $80,000 at $1.00, a fall to $0.995 costs you $400 and a fall to $0.97 costs you $2,400. That is the entire direct loss, and it is smaller than most people fear.
• Government and retail prime funds still price at a stable $1.00; institutional prime and institutional municipal funds have priced at a floating four-decimal NAV since October 2016, so they can print $0.9998 without anyone calling it a crisis.
• The real damage is timing. A mandatory liquidity fee charged on redemptions during heavy outflows comes out of your proceeds on the day you sell, on top of any NAV move.
• Money fund shares settle T+1 like most securities trades, so a fund that suspends same-day wires pushes a Friday closing into the following week even if the price never leaves $1.00.

Why does a money market fund show $1.00 every day when bond prices move constantly?

Because the fund is allowed to round. A money market fund holds short-dated debt: Treasury bills, agency paper, repurchase agreements, commercial paper, bank certificates of deposit. Those instruments move in price every day, in tiny amounts, because they mature in weeks and carry little credit risk. The fund adds up what it owns, divides by shares outstanding, and gets a number like $1.00023 or $0.99987.

Stable-NAV funds report that to two decimal places. Both of those round to $1.00.

That’s the whole trick. There is a corridor, and it’s half a cent wide in each direction. As long as the true value per share sits between $0.995 and $1.005, the printed price is a dollar and your statement never twitches.

Say your fund holds $10 billion across 10 billion shares. Half a cent of cushion on 10 billion shares is $50 million. The fund can lose $50 million of value before the printed price is forced down to $0.99. On a $10 billion portfolio that’s 0.5%. Short paper rarely moves that much on rate changes alone, which is why the price almost never breaks. It takes a default, or a forced sale of assets into a market with no buyers.

What actually pushes a fund through that half-cent corridor?

Two mechanisms, and they’re different.

The first is credit. A holding stops paying. If your fund put 1.5% of assets into one issuer’s commercial paper and that issuer defaults with a 60% recovery, the loss is 1.5% × 40% = 0.6% of the portfolio. That’s 0.6 cents per share, which exceeds the half-cent corridor. Printed price goes to $0.99. Your $80,000 becomes $79,200.

The second is forced selling, and it’s the one that does more damage in practice. Redemptions come in faster than paper matures. The fund can’t wait for its 45-day commercial paper to mature, so it sells at whatever bid exists. In a stressed market the bid on decent short paper can sit a quarter point below where it was marked. Sell 20% of the portfolio at a 0.25% discount and you’ve torched 0.05% of total value, which is half a cent per share on nothing but transaction costs.

Notice that the second mechanism is caused by other shareholders leaving, not by anything wrong with what the fund owns. That’s the part worth understanding, because it’s what the rules are built around.

What happens to your $80,000 as the price steps down?

Track one number the whole way. You own 80,000 shares at $1.00 on a Monday.

All figures are illustrations, computed as 80,000 × the stated price. The $0.97 row references the level the Reserve Primary Fund repriced to in September 2008 after writing off its Lehman Brothers commercial paper; the $0.95 row is invented to show the shape of the curve and does not describe any actual fund.

Look at the second row. True value is $0.9985, which is 0.15% below par, and your statement still says $80,000. You are already down $120 in economic terms and the screen will not tell you. That gap is not fraud. It’s the rounding convention working as designed. It also means the moment the printed price finally moves, it moves by a full cent at once, because the fund was absorbing the drift silently until it couldn’t.

And the 2008 row, the worst well-known case in US money fund history, cost 3%. Three percent. That is a bad week in a stock fund and a catastrophe in a money fund, purely because of what people expected the product to do.

Why is the redemption gate worse than the price drop?

Because $2,400 is survivable and a missed closing date isn’t.

Here’s the sequence. Bad news hits an issuer on Tuesday morning. Institutional holders in the fund read it by 9:15 and start redeeming, because their downside for leaving early is zero and their downside for leaving late is being the shareholder left holding the illiquid paper. Retail holders find out Tuesday evening from a news alert.

By the time you place your redemption Wednesday, the fund has already sold its Treasury bills and its overnight repo, because those sell instantly at full price. What’s left in the portfolio is the harder stuff. You are redeeming against a worse pool than the person who left on Tuesday, and you’re paying for their exit through the transaction costs their exit generated.

That’s the first-mover advantage, and it’s the reason the SEC’s 2023 money market fund reforms attached a mandatory liquidity fee to institutional prime and institutional tax-exempt funds. When net redemptions in a day exceed 5% of net assets, the fund must charge redeeming shareholders a fee reflecting the cost of the liquidity they’re consuming, unless that cost is under 0.01% of the amount redeemed. The point is to make the Tuesday redeemer pay their own exit costs instead of leaving them for you.

If a 0.75% liquidity fee applied to your $80,000 at a $1.00 price, you’d receive $80,000 − $600 = $79,400. If the price had also moved to $0.99, you’d receive $79,200 − $594 = $78,606. Those are illustrations at rates I picked; actual fees are computed from the fund’s own estimated costs on the day.

The same 2023 reform package removed the ability of non-government funds to impose redemption gates that halt redemptions entirely, replacing gates with fees. Government funds and retail funds may still voluntarily adopt fee or gate provisions if they disclose it. Read the prospectus for the specific fund you hold, since the answer differs by fund type and not by fund family.

Does the timing work like a stock trade?

Roughly, and the difference matters when you need the money on a date.

Most US securities trades now settle one business day after the trade, since the SEC shortened the standard settlement cycle from two days to one. The SEC’s announcement of the T+1 rules frames the change as reducing credit and market risk in the gap between trade and settlement. Money market funds are often marketed on same-day or next-day availability, and many honour a same-day wire if you redeem before an early cutoff.

Under stress, that early cutoff is the first thing to go. The fund keeps processing redemptions but stops guaranteeing same-day wires. Nothing about the price has changed. Your Friday closing has still slipped, because a Wednesday redemption that used to land Wednesday afternoon now lands Thursday or Friday, and a wire that lands Friday afternoon does not clear a Friday morning closing.

Which funds can actually break the buck, and which can’t?

Different funds, different rules, and the labels are not intuitive.

Government money market funds hold at least 99.5% of assets in cash, government securities, and repos fully collateralised by government securities. They price at a stable $1.00. Their credit risk is close to zero, so the realistic path to breaking the buck runs through a Treasury payment failure, not through an issuer default.

Retail prime and retail municipal funds limit ownership to natural persons and also price at a stable $1.00. They hold commercial paper and bank paper, so they carry real, if small, credit exposure.

Institutional prime and institutional municipal funds have priced at a floating NAV, carried to four decimals, since October 2016. A share price of $0.9997 in one of these is Tuesday. Nobody calls it breaking the buck, because there was never a buck to break. The four-decimal display is the point: it prices in the drift that stable funds hide.

The paradox is that the transparent funds look scarier and are structurally safer for the shareholder who stays, because departing shareholders sell at the real value instead of at a rounded-up dollar. Every share redeemed at $1.00 when the fund is truly worth $0.9990 removes a tenth of a cent of value from everyone who remains.

What about the fund’s sponsor stepping in?

Sponsors have historically bought impaired paper out of their own money funds at par to keep the price at $1.00. That’s a business decision, not an obligation. Prospectuses state plainly that the fund is not insured or guaranteed by the sponsor, and that you could lose money. Treat sponsor support as a possibility, not as a feature you’re paying for.

Money market funds are also not bank deposits. No FDIC insurance. SIPC coverage protects you if your broker fails and your assets go missing, not if the fund’s investments lose value. FINRA’s overview of how securities differ from insured deposits is worth reading for the general principle, which is that market products carry market risk regardless of how stable they look.

What does this look like from inside your account on the day?

Return to your 80,000 shares. Wednesday.

You log in. Balance says $80,000.00. Same as always. There is a notice on the fund’s page you would only see if you clicked through, saying the fund experienced elevated redemptions and applied a liquidity fee to redemptions processed on that date.

You submit a full redemption at 10:40 in the morning. The cutoff for same-day wires was 9:00, which you didn’t know because it was 3:00 in ordinary times and got moved. Your trade prices at the end of the day.

The NAV that evening is struck at $1.00, because the true value was $0.9982 and the fund still rounds. A 0.40% liquidity fee applies. Your proceeds: 80,000 × $1.00 = $80,000, less $320, equals $79,680. Cash reaches your bank Thursday.

Total cost: $320 and one business day. That’s the realistic version of this event for a retail holder, and it’s why the honest framing is a timing risk rather than a loss risk. The catastrophic version, the 2008 one, cost 3% and locked up money for months while the fund liquidated. It has happened once at scale in this product’s history.

Why does the industry care so much about a 3% loss?

Because of what money funds are used for. Corporate payroll accounts. Escrow. Broker sweep balances. Municipal operating cash. Those balances are spent on schedule, and the schedule doesn’t flex.

A pension fund that loses 3% on an equity allocation adjusts. A company that can’t wire payroll on the 15th has a different kind of problem. That’s why money fund stress spreads: the fund sells commercial paper to meet redemptions, the commercial paper market seizes, and companies that fund inventory with 30-day paper suddenly can’t roll it. The chain runs from a fund’s NAV into the real economy in about a week.

Does leverage anywhere in your account change this?

Yes, and it’s the sharpest edge in the whole topic.

If your money fund balance sits in a brokerage account as a sweep and also counts toward your margin equity, a drop from $1.00 to $0.97 shrinks your equity by 3%. On $80,000 that’s $2,400 of equity gone. If you’re leveraged 2:1 against a $160,000 position, a $2,400 equity loss can be enough to trip a maintenance call, depending on where your equity sat before.

That’s the mechanism most people miss: the cash leg is treated as the risk-free anchor of the account, so nobody models it moving. The SEC’s explainer on borrowing money to pay for stocks sets out that brokers can force a sale without contacting you first and can choose which securities to sell. If the sweep fund is simultaneously gated or delayed, the cash you’d use to meet the call is the cash you can’t reach.

Simultaneous, not sequential. Both problems land on the same morning.

What this does not tell you

The specific numbers here are worked illustrations, not forecasts. I chose $80,000, $0.99, $0.97, 0.40%, and 0.75% to make arithmetic visible. Your fund’s actual liquidity fee, if one applies, is computed from its own estimated trading costs on the day and could be higher or lower.

I have not told you which funds hold what. Portfolio composition changes weekly and is disclosed in each fund’s own monthly holdings filing. The only reliable source for what your fund owns is that fund’s filings and prospectus, not a general article.

I have not modelled a government fund breaking the buck through a Treasury payment disruption. That’s a scenario with no clean historical precedent to calibrate against, and any number I attached to it would be invented.

The rounding corridor of half a cent applies to stable-NAV funds. If you hold an institutional prime fund with a floating four-decimal NAV, the entire framing of this article changes, because you see the drift in real time and the concept of breaking the buck doesn’t apply.

Nothing here says whether holding a money market fund is appropriate for your four-month horizon. That depends on your alternatives, your tax situation, and how hard your date is. I’m describing a mechanism, not a choice.

FAQ

Has a money market fund available to US retail investors ever broken the buck?

Yes, twice in recognised cases. The Reserve Primary Fund repriced to $0.97 in September 2008 after writing its Lehman Brothers commercial paper to zero. A small institutional fund, Community Bankers US Government Money Market Fund, broke the buck in 1994. Two events in decades of operation across thousands of funds is the accurate base rate, and it’s why the risk is best understood as rare and consequential rather than routine.

If the printed price stays at $1.00, am I actually safe?

Not necessarily. The printed price rounds to two decimals, so a fund truly worth $0.9985 per share still shows a dollar. You’re down 0.15% economically and your statement doesn’t reflect it. On 80,000 shares that’s $120 invisible. It matters if you’re deciding whether to stay, because the person redeeming ahead of you takes out the full rounded dollar and leaves the shortfall behind.

Can a fund stop me withdrawing entirely?

Non-government funds no longer use redemption gates under the SEC’s 2023 amendments; mandatory liquidity fees replaced them for institutional prime and institutional tax-exempt funds. Government and retail funds may adopt fee or gate provisions voluntarily, with disclosure. The practical restriction you’re more likely to meet is not a halt but a cutoff change: same-day wires stop, next-day processing continues.

Does a liquidity fee apply to everyone or only to people leaving?

Only to shares actually redeemed on the day the fee is in force. Stay put and you pay nothing. That asymmetry is deliberate. It’s designed so the shareholder consuming the fund’s liquidity pays the cost of producing it, instead of that cost being spread across everyone who stayed.

Is my money market fund covered by FDIC insurance?

No. Money market funds are securities, not deposits, regardless of how the balance is labelled in a brokerage app. SIPC protects against your broker failing and your assets going missing; it does not reimburse investment losses. A bank money market deposit account is a different product with FDIC coverage and a similar name, which is a genuine source of confusion worth checking on your own statement.

How fast does this happen once it starts?

Fast at the top and slow at the bottom. Institutional redemptions build within hours of bad news. Price effects show up in a day or two. But the 2008 case took months to resolve, because liquidating a portfolio of impaired paper in an order that treats shareholders fairly is slow work. Plan around the possibility that your money is unreachable for weeks, not that it’s gone.

What to look at next

Pull up the actual fund on your statement and find three things in its prospectus: whether it’s classified as government, retail, or institutional; whether it prices at a stable $1.00 or a floating four-decimal NAV; and what its stated policy is on liquidity fees. Those three facts determine which half of this article applies to you.

Then find the fund’s same-day redemption cutoff time and note whether the fund reserves the right to change it. That’s the number that decides whether a hard date survives a bad week.

This article is general information, not financial advice. See our disclaimer.

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