QE3 Just Starting to Hit Fed Balance Sheet

Although QE3 was announced almost 2.5 months ago, the mortgages that the Fed has been purchasing have only just started to hit the Fed's balance sheet over the last couple of weeks.  The monetary base has continued to hold flat, but mortgage holdings have ticked ever so slightly higher.

The Fed has agreed to purchase ~$100B worth of mortgages since September, but holdings have only increased by $40B due to the lag in time of settlement for MBS trades.  The fact that the balance sheet has mostly been unchanged suggests that we may not yet have seen the effects of QE3 in securities markets.