The Open Market Operations, or buying and selling of securities by the Federal Reserve, is one of the primary tools used by the central bank in its implementation of monetary policy. Open Market Operations are conducted by the Trading Desk at the New York Federal Reserve Bank. The Trading Desk does not buy and sell everything though, because the range of securities that the Federal Reserve is allowed to deal in is limited. Treasury securities and mortgage backed securities are two of the largest holdings on the Federal Reserve balance sheet.