Apparently Theresa May is pushing for a 2nd Brexit referendum vote.  In other words "this isn't working out, so let's maybe just call the whole thing off."  

There's no telling if this is even remotely true or possible yet, but if Britain were to vote against Brexit at this point, it would be very bad for rates.  Markets are trading the microscopic, distant-future possibility in real time, and it's amounting to another 2bps of losses in 10yr yields and another 2-3 ticks (.06-.09) of losses in MBS.

A few of the early/aggressive lenders may consider negative reprices at current levels, but we could just as easily bounce if a clarification-type headline comes out.