Most economists expect the central bank to scale back the size of its bond purchases by the end of the year, and a sizable amount expect to reduce buying as early as September, according to a Reuters poll.

Of 48 economists who answered a poll question on Friday about when they expected the Fed to cut back on the size of its debt purchases, 42 said they expected this by the end of 2013. Of those, 21 expect reduced purchases to be announced during the third quarter of the year, with 19 specifying the Fed's September policy meeting.