Reuters:  "The Federal Reserve launched another aggressive stimulus program on Thursday, saying it would pump $40 billion into the U.S. economy each month until it saw a sustained upturn in the weak jobs market.  The central bank's decision to tie its controversial bond buying directly to economic conditions was an unprecedented step that marked a big escalation in its efforts to drive U.S. unemployment lower."   http://www.reuters.com/article/2012/09/14/us-usa-fed-idUSBRE88C04T20120914