The US Treasury will purchase up to $6 billion of longer-dated government debt on Thursday, the first operation under Secretary Scott Bessent's expanded program to curb rising borrowing costs. The maximum size is triple the $2 billion initially communicated to investors in early August, a plan discarded in a surprise Aug. 19 announcement that the Treasury would "at least double" the operation's size. Treasuries maturing in 20-to-30 years extended their selloff after the announcement, with the 30-year yield hitting a session high of 5.38%, near the month's peak of almost 5.40% — the highest since 2007.

Bond yields have climbed worldwide on higher energy costs since the US's war with Iran erupted in late February, flipping the outlook for Federal Reserve monetary policy. Chairman Kevin Warsh raised overnight interest rates for the first time since 2023 last week to help tame price pressures. Bessent defended his move to upsize the buybacks, saying on CNBC Monday that he acted after markets appeared to be "moving away" from equilibrium prices.

The Institute of International Finance warned that interventions such as purchasing securities in the secondary market "may provide temporary relief, but they cannot resolve the structural drivers of rising debt." After the Sept. 9 upsized buyback announcement, the Treasury chose not to fill the maximum amount, buying only around $5.2 billion of debt maturing in 10-to-20 years due to a lack of competitive bids.