After spending much of the last six years purchasing trillions of dollars of bonds in efforts to help revive the American economy, the Federal Reserve is going to be curtailing the purchases, the New York Times reported today. While this marks the third time since 2008 that the Fed has announced such a move, the central bank said yesterday that the economy no longer needed quite so much help, signaling to many analysts an important milestone in the nation’s painfully slow recovery from the Great Recession. The Fed still plans to keep short-term interest rates near zero for a “considerable time,” it said in a statement after a two-day meeting of its policy-making committee. And it said it would replace maturing bonds to keep its holdings at about $4.5 trillion.