Prime rate (or prime interest rate)
The prime rate used to be defined as the interest rate at which banks lend to their most creditworthy (prime) customers. Now, it is simply an index that is 3 percentage points above the federal funds rate set by the Federal Reserve. Banks set their own rates, but tend to move in unison. The most common measure of the prime rate is The Wall Street Journal prime rate, which surveys banks on their prime rates. Variable rate credit cards are usually pegged to the prime rate, with the cards’ rates set at the prime plus a margin. Today, most bank cards are variable cards with rates pegged to the prime, which means that when the prime rate goes up, most credit card rates will swiftly go up, too.