Although we don't typically publish "alerts" to the MBS Commentary channel (because of MBS Live), today feels like a good day to break those rules considering the sheer level of destruction we're witnessing.  The day itself isn't on the scale of 'Black Wednesday' in May 2009, but the month of May 2013 has been far worse, and is now, in fact, the steepest month of losses for current coupon MBS that we have on record since 2008.  It's slightly delayed from it's original 3:18pm publish time, but here's the most recent alert from MBS Live

"MBS have been watching Treasuries flirt with the idea of breaking 2.137 with a good amount of composure, but have begun to break down now that the deed is done. 10's are up to 2.15 already and Fannie 3.0s and 3.5s are into new lows on the day. Reprice risk remains on the table and could pick up significantly in the next few minutes if we fall further."

Indeed we have fallen further with Fannie 3.0s down 36 ticks (1.125 points) to  100-13.  They're pretty much 'off the island,' at these prices with little chance of redemption today.  Fannie 3.5s are closing in on a full point loss, down 29 ticks at 103-19.  10yr Treasuries are up to 2.15+.  More to follow later today with the normal MBS RECAP...