UMBS 5.0 closed at 99.39, up 24 basis points from Monday's close at 99.15. The 10-year Treasury yield ended the day at 4.247%, down 4.5 basis points. The 30-year survey rate closed at 6.33%, the lowest level in four weeks.

The catalyst arrived around 10 AM: a Fox News report quoted a senior administration official saying there were "all the ingredients of a deal" on Iran, though it wasn't done yet. Oil dropped immediately, bonds followed, and stocks reversed the war-related losses that started in early March. The move is war-headline driven — not data driven. PPI came in well below forecast this morning (headline 0.5% vs 1.1% expected, core 0.1% vs 0.5% expected) and the bond market barely moved on the print. That tells you where the actual driver is. Oil gave it, Iran can take it back.

For borrowers, 6.33% is a four-week low and a real number. The risk in floating from here is asymmetric — gains since early April have come in two-day runs, then reversed. Monday and Tuesday are both positive. The pattern from the past six weeks says Wednesday is the decision point. If the Iran deal signal holds through the week, rates have room to move lower. If negotiations stall or the news reverses, this morning's gains unwind quickly. Locking at a four-week low removes the regret scenario; floating from here is a bet on the geopolitical calendar.

— David Burson, NetRate Mortgage