The supplementary leverage ratio came into sharp focus in the bond slump today and there was talk of extending ahead of Powell. It may be partly responsible (along with Japanese selling) for the mess in the repo market.
The exemption ends on March 31. It was a regulatory break that helped big banks and if it expires banks will have to hold more capital against Treasury bonds, as well as deposits they keep at the Fed.
The knock-on effect means they might just sell bonds to comply. That may be what's been happening in the past few weeks. Or if banks are caught off guard, the selling could come at month end.
This came out 3 hours ago and might have been responsible for the pre-NFP rise in yields.
More on the SLR at Reuters. It will be a key part of the March 17 FOMC decision.