The bulk of all money transactions today involve the transfer of bank deposits. Depository institutions, which we normally call banks, are at very the center of our monetary system. Thus a basic knowledge of the banking system is essential to an understanding of how money works.
Bank Deposits and Reserves
The monetary base is created by the Fed when it buys securities for its own portfolio. Bank deposits themselves are not base money, rather they are claims on base money. A bank must hold reserves of base money in order to meet its depositors' cash withdrawals and to cover the checks written against their accounts. Reserves comprise a bank's vault cash and what it holds on deposit at the Fed, known as Fed funds. The Fed requires banks to maintain reserves of at least 10% of their demand deposits, averaged over successive 14-day periods.
The Movement of Bank Reserves
When a depositor writes a check against his account, his bank must surrender that amount in reserves to the payee’s bank for the check to clear. Reserves are constantly moving from one bank to another as checks are written and cleared. At the end of the day, some banks will be short of reserves and others long. Banks redistribute reserves among themselves by trading in the Fed funds market. Those long on reserves will normally lend to those short. The annualized interest rate on interbank loans is known as the Fed funds rate, and varies with supply and demand.
The reserve requirement applies only to the bank's demand deposits, not its term or savings deposits. Thus when a bank depositor converts funds in a demand deposit into a term or savings deposit, he frees up the reserves that were held against the demand deposit.
