2pm is a hot-bed of activity for algorithmic trading programs (lots of closing of positions that were only intended to be open for the day, and lots of attempts to capitalize on the final hour of CME pit trading (which closes at 3pm ET).  On quiet days with nothing else on the econ calendar and no major headlines hitting the wires, the effects can be especially noticeable.  Today is one of those days.

10yr yields have fallen several bps in relatively short order, now down to 2.886% from earlier highs over 2.91%.  They're still in negative territory on the day, but only by about 1.5bps now.  Fannie 3.5 MBS have nearly broken even, up from 99-20 (99.6) to 99-26 (99.78) currently.  

A few of the faster-moving lenders (in terms of willingness to reprice) could be considering positive reprices.