The U.S. Federal Reserve said Thursday it would go on a buying spree, spending $85 billion per month until the end of the year. The Fed said the Open Market Committee had agreed to buy mortgage-backed securities at a pace of $40 billion per month and \"extend the average maturity of its holdings of securities as announced in June,\" which is a program of turning over the proceeds of short-term maturing bonds into purchases of long-term bonds, a step known as an operational twist. In addition, the Fed said it would maintain an existing policy of reinvesting principal payments from its debt portfolio in agency mortgage-backed securities. The actions, valued at about $85 billion each month, \"should put downward pressure on longer-term interest rates, support mortgage markets, and help to make broader financial conditions more accomodative,\" the Fed said. The FOMC also noted that it would keep its overnight refund rate at the historic low of zero to 0.25 percent, and said that would \"likely to be warranted at least through mid-2015,\" which extends its estimate of how long the central bank\'s key interest rate would be held close to zero. The Fed was under considerable pressure to take action this week, as Fed Chairman Ben Bernanke endorsed making a move in speeches should the economy not find more traction. In addition, the European Central Bank took a dramatic step after its most recent policy meeting, announcing it would buy bonds in certain conditions from countries struggling to climb out of debt.