Central banks use several different methods to increase (or decrease) the amount of money in the banking system. These actions are referred to as monetary policy. While the Federal Reserve Board (the Fed) could print paper currency at its discretion in an effort to increase the amount of money in the economy, this is not the measure used.
Below are three methods the Fed uses in order to inject (or withdraw) money from the economy.
Modifying Reserve Requirements
The Fed can influence the money supply by modifying reserve requirements, which generally refer to the amount of funds banks must hold against deposits in bank accounts. By lowering the reserve requirements, banks are able to loan more money, which increases the overall supply of money in the economy.
Conversely, by raising the banks' reserve requirements, the Fed is able to decrease the size of the money supply.
How Do Central Banks Inject Money Into The Economy?
Changing Short-Term Interest Rates
The Fed can also alter the money supply by changing short-term interest rates. By lowering (or raising) the discount rate that banks pay on short-term loans from the Federal Reserve Bank, the Fed is able to effectively increase (or decrease) the liquidity of money.
Lower rates increase the money supply and boost economic activity; however, decreases in interest rates fuel inflation, and so the Fed must be careful not to lower interest rates too much for too long.
Conducting Open Market Operations
Lastly, the Fed can affect the money supply by conducting open market operations, which affects the federal funds rate. In open operations, the Fed buys and sells government securities in the open market. If the Fed wants to increase the money supply, it buys government bonds. This supplies the securities dealers who sell the bonds with cash, increasing the overall money supply.
Conversely, if the Fed wants to decrease the money supply, it sells bonds from its account, thus taking in cash and removing money from the economic system.
To learn more about central banks and their role in monetary policy, check out Formulating Monetary Policy. For a one-stop shop on subprime mortgages and the subprime meltdown, check out the Subprime Mortgages Feature.