What it means
The slang is old, and the usual explanation traces it to deerskins traded as a unit of value in colonial America. Whatever the origin, a buck has meant a dollar in American English for well over a century, and the usage travels wherever dollars are quoted.
Scale matters when you hear it on a trading floor. In ordinary speech a buck is one dollar, while on some dealing desks a buck means one million dollars, so a trader who says they bought five bucks of a bond means five million.
The only safe course is to confirm the unit before anyone writes it on a ticket. The phrase to break the buck belongs to money market funds, which aim to hold a stable value of one dollar per share.
If the fund's assets fall far enough in value, that figure drops below a dollar and investors who thought their cash was untouchable discover a small loss. This is not a theoretical worry for a finance team.
Treasury policies often allow surplus cash to sit in money market funds, so the policy should say what happens if a fund breaks the buck and who has authority to move the money. A few other phrases use the same word.
Bang for your buck means value for money, big bucks means a large sum, and to pass the buck means pushing responsibility onto somebody else, which has nothing to do with currency at all. Use the word with care in formal writing.
Slang is fine in a meeting and out of place in a board paper or a contract, where the amount and the currency belong in full.
In practice
Real-world examples.
Example
A junior dealer on a fixed income desk is told to buy two bucks of a corporate bond and places an order for two dollars of nominal. The trade is corrected before settlement, and the desk head adds a rule that all order sizes are written in figures with the currency stated.
Example
A manufacturing group keeps $40,000,000 of surplus cash in money market funds. Its treasury policy sets a limit of $10,000,000 per fund and requires the treasurer to move balances within one business day if any fund's value per share falls below $0.9975, so no single fund breaking the buck can do serious harm.
Example
A marketing agency pitching a retainer leads with the phrase more bang for your buck and then shows the arithmetic: the same $8,000 monthly fee covering four campaigns instead of two. The slang gets attention, and the numbers behind it win the work.
Formula
Calculation
The calculation worth knowing is the net asset value per share of a money market fund: net asset value per share = (total assets - total liabilities) divided by shares in issue. Take a fund with total assets of $996,000,000, liabilities of $2,000,000 and 1,000,000,000 shares in issue. Net assets are 996,000,000 - 2,000,000, which is $994,000,000, so the value per share is 994,000,000 divided by 1,000,000,000, which is $0.994. That sits below $1.00, so the fund has broken the buck. An investor holding 10,000,000 shares now has 10,000,000 times 0.994, which is $9,940,000, rather than the $10,000,000 they expected, a shortfall of $60,000.Case study
Seen in the real world.
Northwind Analytics is an invented data business used for this illustrative case. It had raised $25,000,000 and parked almost all of it in a single money market fund, on the reasonable view that such funds behave like a bank account.
During a short credit squeeze the fund suspended withdrawals for nine days and its value per share dipped to $0.997. Northwind lost about $75,000 of value, which was survivable, but it could not pay a scheduled $3,000,000 instalment on a building fit-out and had to ask the contractor for time.
The fictional lesson was about access rather than loss. Northwind rewrote its policy to split cash across three funds and one bank deposit, so that a fund breaking the buck or gating withdrawals could never stop it paying a bill.
Watch out
Common mistakes.
- Assuming a buck always means one dollar, when on some trading desks it is shorthand for one million and the difference is six zeros.
- Treating a money market fund as identical to a bank deposit, when its value per share can fall below a dollar and withdrawals can be restricted.
- Using slang such as bucks in contracts, board papers or invoices, where an unambiguous figure and currency are needed.
Questions
People also ask.
What does it mean to break the buck?
It means a money market fund's net asset value per share has fallen below $1.00, so investors would get back slightly less than they put in.
Is a buck always a United States dollar?
In finance, yes by default, although the word gets borrowed loosely for other dollar currencies, which is one more reason to state the currency explicitly.
Where does the word come from?
The widely accepted explanation is the trade in deerskins used as a unit of value in early America, though the trail is not documented precisely enough to be certain.
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