As we tick across the official 3pm close, we're back down to earlier price levels with the 4.5 at 100-23.  We'll let you know if we lose any ground from here.  Stocks are positive to the tune of 112.38 right now, and tsy yields are backing up a bit, both potentially pressuring MBS to whatever extent the connection remains.  Stay tuned as reprices for the worse are possible as these are the lows of the day (although narrow trading range).