Coming off of yesterday's excellent performance, today's bond market selling-spree felt jarring--probably more jarring than it actually was.  Right off the bat, consider that yesterday afternoon saw a very late improvement in both Treasuries and MBS.  This improvement set a high bar for today's "day-over-day change."  You can see this in the following chart as the MBS prices that trade over the teal line.  

That late rally didn't result in any appreciable surge of reprices, so why not throw it out as a critical component of the 2-day outlook?  That gets us more than halfway back to "unchanged on the day."  From there, we can consider that MBS prices never went below yesterday afternoon's lows (red line in the chart above).  As such the takeaway is that mortgage markets were essentially flat compared to yesterday--a fact that's reflected in today's rate sheets.

Of course the bigger question is whether or not rates have bounced (again) at the bottom of 2017's range.  For the answer to that question, we'll likely need to wait to see how the rest of the week's data and events play out.  The biggest event on the near-term horizon is tomorrow's release of the Minutes from the most recent Fed meeting.  I don't think these are necessarily guaranteed to cause a big commotion, but traders could nonetheless be waiting to see what they contain before getting onboard with the next bout of bond market momentum.