Black box selling in Treasury futures is led Treasuries to their weakest levels of the day just now. MBS are doing their best to keep up with the move despite what continues to be generally poor liquidity. All that to say, there is no overt headline-related reason for the current selling.
Lack of causality aside, the losses are enough that some lenders who priced near the earlier highs (930-1030am) could be considering a negative reprice risk. Fannie 4.0s are now down to 103-11 from 101-17. 10yr yields are at their highs of the day at 2.879.