The Federal Reserve has taken many unprecedented steps in the past four years to try to boost the U.S. economy and counter the effects of a financial crisis that triggered a painful recession. It has kept the short-term interest rate it controls at a record low near zero since December 2008. It’s bought more than $2 trillion in U.S. Treasurys and mortgage bonds to try to hold down longer-term rates. Those purchases have increased the Fed’s balance sheet to more than $2.8 trillion. (full story)