Prime Rate vs Federal Funds Rate
Prime Rate and Federal Funds Rate are related concepts in AP Economics that students often mix up. The prime rate is the benchmark interest rate banks charge their most creditworthy customers; it tracks the federal funds rate, usually running about 3 percentage points above it. The federal funds rate is the interest rate at which banks lend their excess reserves to other banks overnight. Here is how they compare side by side.
Banks set the prime rate themselves, but they peg it to the FOMC's federal funds target, so when the Fed moves rates the prime rate moves with them. Many consumer and small-business loans (credit cards, HELOCs, variable loans) are priced as 'prime plus a margin,' which is how Fed policy reaches everyday borrowers. The prime rate is not set by the Fed directly.
The Federal Open Market Committee sets a target for this rate to influence borrowing costs across the economy. Changes in the federal funds rate affect consumer and business loans, investment, and overall economic growth. It is the primary tool the Fed uses to implement monetary policy.
Prime Rate vs Federal Funds Rate: A Posted Rate and an Interbank Rate
| Prime Rate | Federal Funds Rate | |
|---|---|---|
| Who pays it | A bank's strongest business and household borrowers | Banks borrowing reserves from other banks |
| Who sets it | Each bank posts its own, and banks move together | Trading between banks, inside the central bank's target range |
| Length of the loan | Credit lines and loans lasting months or years | Overnight |
| Level | Higher, since it carries credit risk and a margin | Lower, since the loan is overnight and made to a bank |
| What moves it | The policy target, by a conventional markup | Policy decisions and the supply of reserves |
| What it is used for | Pricing credit cards, home equity lines and small business loans | Signalling the stance of monetary policy |
| Who publishes it | Banks themselves, and surveys that collect their quotes | The central bank, as an average of actual trades |
The prime rate is a markup, so policy passes straight through to borrowers
Banks have conventionally quoted prime as the policy target plus a fixed markup rather than letting it float with supply and demand. Use illustrative numbers to see the chain. Suppose the target is 4 percent and banks quote prime at the target plus 3 percentage points, so prime is 7 percent. A small business credit line priced at prime plus 2 then costs 9 percent. Raise the target by a point, to 5 percent, and prime moves to 8 percent and the credit line to 10 percent. On a $50,000 balance the annual interest goes from $4,500 to $5,000, since 9 percent of $50,000 is $4,500 and 10 percent is $5,000. The borrower pays $500 more for a decision made about an overnight interbank market they have never touched. This is why prime is a useful teaching example of the /glossary/monetary-policy-transmission-mechanism. The markup is convention rather than law, and it can widen when banks become cautious about lending, which is one reason a rate cut does not always reach borrowers in full. The size of the markup used above is chosen for the arithmetic and should not be treated as a fixed feature of any banking system.
One rate prices risk, the other prices reserves
The gap between the two rates is not arbitrary. An overnight loan of reserves to another bank is about as safe as private lending gets: it lasts one night and the borrower is a supervised institution with an account at the central bank. A three year business loan carries /glossary/credit-risk, takes years to repay, and ties up capital the bank must hold against it. The higher rate compensates for all of that, plus the bank's operating costs and profit margin. Two implications follow. First, prime never falls to the policy rate, however low the policy rate goes, because the risk and the term do not disappear. Second, prime is not really a market price at all; it is a posted number that individual banks choose, and its value comes from being a shared reference point rather than from any trading. That makes it convenient as a base for contracts, since a loan agreement can say prime plus two and adjust automatically. It also means the reference can move for reasons that have nothing to do with a single borrower's own creditworthiness.
Frequently asked questions
What is the difference between the prime rate and the federal funds rate?
The federal funds rate is what banks charge each other for overnight loans of reserves, while the prime rate is what a bank charges its most creditworthy customers for ordinary loans. The prime rate sits well above the funds rate because it covers credit risk, a longer term and the bank's own margin.
Why does the prime rate move when the Fed changes rates?
Because banks set prime as a conventional markup over the policy target rather than through trading, so a change in the target passes into prime almost immediately. Loans and credit lines priced as prime plus a spread then reprice automatically, which is one of the fastest channels from policy to household and small business borrowing costs.
Is the prime rate the lowest rate a bank charges?
It is the benchmark for a bank's strongest borrowers, but large corporations can often borrow more cheaply by issuing their own short term debt in the market. Prime is best understood as a reference point for smaller loans and credit lines rather than as an absolute floor on what anyone can pay.
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