MBS have been in rally mode all day long.  Here's the reprice alert from MBS Live:

Positive Reprices Reported, More Possible if Current Levels Hold 12:48PM

The uptrend that began this morning has continued steadily into the afternoon. Benchmark 10yr yields broke through resistance at 2.03+ and Fannie 3.5 MBS broke back above the important 101-16 and currently sit 2 ticks better on the day at 101-21. A few of the early lenders have already repriced for the better. A few more might reprice at these levels with a majority getting on board around 101-26 levels.

As you can see in the video, MBS indeed achieved the 101-26 levels, and just about every lender under the sun has repriced for the better (some of them 2-3 times).  As far as the importance of 101-26 in the long run (because the 2 day chart doesn't quite do it justice), here are a few different ways to look at it:

The preceding chart shows also gives a clear sense of the 101-16 level's importance.  The next chart is even longer term, and shows how 101-26 acted as a ceiling when MBS first entered current territory, and perhaps even hints at the possibility that MBS have been trying to settle in on a range that's centered on 101-26.

Treasuries have experienced the highs and lows of their November range in a matter of hours (not absolute highs and lows, but the 1.95 and 2.07+ technical boundaries from this morning's and other recent charts.

The rally is largely disconnected from the stock lever (as was the selling that began after the 3pm close on Wednesday.  It's almost as if the money that mattered in Treasuries left for the weekend at the expected time, got back this morning, and have been in the process of getting things back down to Wednesday levels ever since.  Oversimplification of reality, but maybe less so than we might assume).  S&P's seem to merely have been fairly flat relative to Treasuries.

This chart actually gives the best sense of the disconnect between stocks and bonds in terms of RELATIVE movement: