WASHINGTON (MarketWatch) -- The Federal Reserve on Wednesday said it will sell $400 billion worth of short-maturity bonds it holds and reinvest in bonds maturing between 6 and 30 years by the end of June 2012, confirming market expectations that it would revive the 1960s-era program dubbed "Operation Twist." By a 7-to-3 vote, the Fed also said it will reinvest proceeds from maturing mortgage-backed securities into mortgage-backed securities, instead of its previous practice to buy Treasurys with the proceeds. The Fed kept its target Federal funds rate between 0% and 0.25% and kept its pledge, first announced in August, to keep rates at exceptionally low levels through the middle of 2013. The Fed said that "economic growth remains slow" and inflation will settle at or below levels consistent with its dual mandate.