By Jared Blikre

Uncle Sam is buying more of his own debt. The surprising part isn't how much — it's why Scott Bessent's Treasury decided to act now.

The US Treasury unexpectedly said Wednesday that it will step up purchases of long-term government bonds, giving a stressed corner of the market more support.

The bond market responded immediately. The 30-year Treasury yield (^TYX) fell to 5.20%, its biggest one-day drop in more than three weeks. The dollar index (DX-Y.NYB) was down 0.75%, its most since July 30.

The timing is what makes the move unusual.

Only two weeks ago, Treasury laid out its normal quarterly financing plan and left its long-term buyback cap at $2 billion. Wednesday, it said that cap would rise to at least $4 billion beginning Sept. 9 — well before the next scheduled update in November.

And Treasury already knew Wall Street wanted to sell it far more bonds than it was buying.

Read more: How soaring Treasury yields could impact your finances

US Treasury, Yahoo Finance analysis

For every $1 Treasury was prepared to spend buying older long-term bonds, investors routinely offered more than $10. The multiple peaked around 18x this spring and had actually cooled to 11x by late July.

So the offer pile of bonds wasn't suddenly getting bigger. Treasury's willingness to take more of it was.

The program itself is not new. Treasury launched regular buybacks in 2024 and has gradually expanded them, including increasing the frequency of long-term operations last year.

Think of it loosely like a corporate stock buyback, except the Treasury is buying bonds rather than stock — and the goal isn't to lift their price. It mostly buys older bonds that are harder to trade, freeing dealers to keep more bonds moving through the market.

That puts Treasury Secretary Scott Bessent in an interesting position opposite Fed Chairman Kevin Warsh.

Warsh has deliberately tried to let markets speak for themselves. At his July press conference, he said the Fed was trying to get an "unfiltered message from markets," allowing "buyers and sellers [to] meet at prices for Treasurys" rather than interfering with that signal.

Bessent just stepped in anyway.

Long-term borrowing costs have climbed back into a zone that has repeatedly rattled stocks, housing, and other rate-sensitive markets. Yahoo Finance AlphaSpace