The quantity of dollars, monitored and heavily influenced (if not controlled) by the Federal Reserve. There are three components of money supply: M1, the most basic measure, consists of currency, checking accounts, money market funds, NOW accounts and travelers checks. M1 is what the Fed watches most closely, and what it can most immediately influence by buying or selling Treasury securities. M2 is everything in M1 plus time deposits exceeding $100,000 and repurchase agreements. M3 is even broader, encompassing M2 as well as savings bonds, Treasury bills, commercial paper, Eurodollars and more.