The Federal Reserve System

To understand how the Fed uses the discount rate to control the money supply, let's return to our earlier discussion of reserves. Recall that banks must keep a certain fraction of their deposits as reserves. The bank can hold these reserve funds or deposit them into a Federal Reserve Bank account. Recall, too, that the bank can lend out any funds that it doesn't have to put on reserve. What happens if a bank's reserves fall below the required level? The Fed steps in, permitting the bank to "borrow" reserve funds from the Federal Reserve Bank and add them to its reserve account at the Bank. There's a catch: the bank must pay interest on the borrowed money. The rate of interest that the Fed charges member banks is called the discount rate. By manipulating this rate, the Fed can make it appealing or unappealing to borrow funds. If the rate is high enough, banks will be reluctant to borrow. Because they don't want to drain their reserves, they cut back on lending. The money supply, therefore, decreases. By contrast, when the discount rate is low, banks are more willing to borrow because they're less concerned about draining their reserves. Holding fewer excess reserves, they lend out a higher percentage of their funds, thereby increasing the money supply.

Even more important is the carryover effect of a change in the discount rate to the overall level of interest rates. When the Fed adjusts the discount rate, it's telling the financial community where it thinks the economy is headed - up or down. Wall Street, for example, generally reacts unfavorably to an increase in the discount rate. Why? Because the increase means that interest rates will probably rise, making future borrowing more expensive.