"To help support the economic recovery in a context of price stability, the Committee will keep constant the Federal Reserve's holdings of securities at their current level by reinvesting principal payments from agency debt and agency mortgage-backed securities in longer-term Treasury securities. The Committee will continue to roll over the Federal Reserve's holdings of Treasury securities as they mature".
During the financial crisis the Fed dramatically expanded its balance sheet. A good description of Fed actions is provided here http://research.stlouisfed.org/publications/review/09/03/Gavin.pdf.
The chart (data from Cleveland Fed) below highlights recent changes in Fed's balance sheet. As the Fed plans to keep its total level of securities' holdings at the current elevated levels (and increases the fraction going to long-term treasuries), it leads one to wonder about the consequences two or three years down the road.
