The refunding tells the market the size of upcoming auctions and the mix between short treasury-bill issuance and longer coupon issuance. That mix is effectively a duration supply decision, and the long end prices it immediately.
A shift toward bills funds the deficit without adding duration, which supports long bonds. A shift toward 10s and 30s forces the private sector to absorb more interest-rate risk, which usually pushes term-premium and long yields up. Since 2023 the QRA has been one of the highest-impact scheduled events in the rates calendar.
Example: the Treasury guides to $125 billion of coupon issuance versus $114 billion expected, with the increment weighted to 10s and 30s. The 30-year sells off 8 basis points on the release and the curve bear steepens.
Related: treasury-auction, term-premium, treasury-bond, bear-steepener, debt-ceiling