Money market instruments are short-term financial claims and borrowing arrangements, generally with original maturities of one year or less. In the United States, they include Treasury bills, commercial paper, certificates of deposit, federal funds borrowing, and repurchase agreements. They help governments, banks, companies, and securities dealers manage near-term funding, while the rates and liquidity in these markets are part of how Federal Reserve policy reaches the broader economy.
What are money market instruments?
The Federal Reserve defines money markets as the part of financial markets where short-term borrowing and lending takes place, with original maturities of one year or less. Typical instruments are short-term, relatively liquid, and often considered to carry limited credit risk, but that is a general description—not a guarantee. Risk depends on the borrower or issuer, any collateral, the contract terms, and market conditions. Federal Reserve glossary; FOMC staff memo, July 13, 2016.
These instruments are not all the same kind of promise. Some are securities issued to raise cash, some are bank deposits or interbank loans, and repos are transactions that function economically like collateralized loans. A useful comparison asks who borrows, whether the funding is secured, when it matures, how readily it can be traded or repaid, and what credit exposure the holder takes.
Main types of money market instruments
| Instrument | Issuer or borrower and structure | Maturity and liquidity | Typical funding purpose and credit exposure |
|---|---|---|---|
| Treasury bills | Short-term marketable securities issued by the U.S. Treasury; not collateralized borrowing by a private issuer. | Original maturity of one year or less. They are widely traded, though liquidity can vary with market conditions. | Raise short-term federal funding. Exposure is to the U.S. Treasury rather than a bank or company. Federal Reserve glossary; Federal Reserve Financial Accounts instrument descriptions. |
| Commercial paper | Short-term promissory notes issued by financial and nonfinancial borrowers; may be secured or unsecured. | 1 to 270 days, with a typical maturity of about 30 days — Board of Governors of the Federal Reserve System, 2026. Often issued at a discount, with face value paid at maturity. | Provides direct short-term funding for business operations and financial activity. Credit exposure depends on the issuer and whether the paper is secured. Federal Reserve Financial Accounts instrument descriptions. |
| Certificates of deposit (CDs) | Bank deposit instruments that can be traded in money markets. | Terms vary; the cited Federal Reserve materials do not state a single standard maturity or liquidity level. | Provide bank funding; holders take exposure to the issuing bank. A negotiable CD is not interchangeable with a money market deposit account. Federal Reserve glossary; Federal Reserve Financial Accounts sector descriptions. |
| Federal funds | Short-term unsecured borrowing among banks. | Typically overnight in the market discussed by the Federal Reserve; terms and liquidity depend on the transaction and conditions. | Meet near-term funding needs. The borrowing is unsecured, so exposure is to the borrowing bank. FOMC staff memo, July 13, 2016. |
| Repurchase agreements (repos) | A seller transfers securities and agrees to repurchase them later; economically, the transaction is a collateralized loan. | Often short-term, including overnight transactions; liquidity and collateral terms vary. | Borrowers obtain cash against securities. Dealers use repo funding for Treasury inventories and other securities holdings; the lender’s credit exposure is mitigated by collateral, but not eliminated. Federal Reserve research note, August 26, 2026; Federal Reserve open market operations overview. |
| Bankers’ acceptances | A bank accepts a draft or bill and promises payment on a future date. | Short-term; the cited Federal Reserve description does not give one standard maturity. | Can facilitate payment and trade financing. The bank’s acceptance creates a payment obligation. Federal Reserve Financial Accounts instrument descriptions. |
Money market funds can also hold agency- and government-sponsored enterprise-backed securities, short-term municipal securities, and other liquid assets. These holdings are not all identical in issuer, collateral, or risk. The categories above are not a universal safety ranking: for any specific instrument, examine who owes the money, the security behind the claim, its terms, and the conditions in the market where it trades.
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How a repo and reverse repo work
In a repo, one party sells securities for cash and agrees to buy them back later at a higher price. The difference between the sale and repurchase prices reflects the interest on the cash loan. Although the legal form is a securities sale and later repurchase, the Federal Reserve describes the transaction as economically equivalent to a collateralized loan.
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A reverse repo describes the same transaction from the other side: the party buying the security and agreeing to sell it back later is effectively lending cash against collateral. Whether a transaction is called a repo or reverse repo depends on which party’s perspective is being described. Federal Reserve open market operations overview.
Money market instruments are not money market funds
An instrument is a financial claim or funding transaction. A money market fund is an investment vehicle that pools investors’ money and holds a portfolio of short-term liquid assets. U.S. funds may hold Treasury and agency securities, CDs, commercial paper, short-term municipal securities, and repos; their dividends reflect short-term interest rates. Federal Reserve Financial Accounts, June 11, 2026.
In the United States, money market funds are registered open-end investment companies regulated under the Investment Company Act of 1940 and subject to Rule 2a-7. The Federal Reserve’s Financial Accounts documentation describes risk-limiting requirements that include a 60-day-or-less limit on average portfolio maturity, issuer concentration limits, and minimum readily convertible assets. These rules do not make a fund a bank account or eliminate investment risk. Money market fund balances are not insured by any federal agency. Federal Reserve Financial Accounts, June 11, 2026.
How money market instruments affect the economy
They fund business activity and credit
Commercial paper gives financial and nonfinancial borrowers a way to raise short-term cash. That funding can support companies’ operating liquidity and financial activity tied to consumer credit, including auto loans and mortgages. If short-term funding becomes more costly or harder to obtain, borrowers may face pressure to manage cash or finance activity differently. Federal Reserve funding and liquidity facilities overview.
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They support securities-market financing and liquidity
Repos let dealers finance Treasury inventories and other securities positions rather than pay for them entirely with their own cash. The Federal Reserve describes the overnight Treasury repo market as supporting Treasury market liquidity and price discovery. Its August 26, 2026 note reports more than $8 trillion in daily trading volume for the overnight Treasury repo market; that figure describes this particular market, not all money markets. Federal Reserve research note, August 26, 2026.
They help transmit monetary policy
Money market rates reflect the cost and availability of short-term funding. Because banks and other financial institutions borrow and lend in these markets, changes in overnight rates can influence broader financing conditions. The Federal Reserve uses tools that operate in these markets as part of monetary policy implementation: overnight reverse repo operations help keep the federal funds rate within the FOMC’s target range, while standing repo operations provide liquidity to eligible counterparties and help limit upward pressure in overnight funding markets. Federal Reserve open market operations overview; Federal Reserve standing repo operations overview, updated December 15, 2025.
They can transmit stress as well as funding
Money markets depend on participants being willing and able to provide cash. Sudden shifts in demand or supply can create liquidity pressure, making it harder for borrowers to roll over short-term funding or for investors to sell assets without disruption. Federal Reserve facilities established in 2020 to support credit and market functioning—including commercial paper funding and money market fund redemptions—illustrate how stress in these channels can reach businesses and investors. Those were historical emergency measures, not evidence that the same facilities are currently available. Federal Reserve funding and liquidity facilities overview.
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How to assess a specific instrument
- Identify the borrower or issuer. A Treasury bill, bank CD, and corporate note create different credit exposures.
- Check whether the claim is secured. Repo lending is backed by securities collateral; federal funds are unsecured, and commercial paper may be secured or unsecured.
- Read the maturity and terms. Short original maturity is a defining feature of money markets, but the actual maturity and renewal terms still matter.
- Consider liquidity in context. An instrument may generally trade in a liquid market without being equally easy to sell in every market condition.
- Distinguish direct holdings from fund shares. A fund owns a portfolio of instruments; an investor in the fund owns fund shares and does not receive federal deposit insurance.
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