It's been a fairly rough day for MBS so far.  3.5 MBS coupons are not trading with much liquidity, and as the lone buyer of size, the Fed's daily allotment of MBS bid isn't enough to offset the supply.  As such, MBS have generally been weakening vs Treasuries today.  The latter have generally been doing a good job of demonstrating some sideways support after recently having broken out of their bearish trend.

Yes that's right...  I really did just say that Treasuries have broken out of their bearish trend.  That's not to say they'll STAY sideways or improve, but that's what they've been doing so far.  Here's what it looks like:

Revisiting the retracement levels from The highest and lowest yields since 8/1, we see 2.23 and 2.11 line up with two of the teal lines in the chart above (yes, 2.11 is not the same as 2.12, but you should be able to see the broader pivot behavior around that general area)

Last but not least, here's a longer term look at MBS... Just barely holding on to the 100-23/100-28 range mentioned a few days ago. MBS generally weaker on the day vs TSY's generally stronger.