US Treasuries Post Worst Month in Four Years

The trigger was data, not sentiment. According to the Financial Times, figures published on 30 September 2026 showed the US economy grew faster than previously estimated, pushing bond markets into a fresh sell-off. Personal consumption expenditures inflation did fall in the same release, which might ordinarily have offered some relief to holders of longer-dated paper, but the growth revision dominated. Stronger growth reduces the urgency for the Federal Reserve to cut rates, and a market already leaning short had little reason to reverse.

What the FT describes as a "vicious loop" follows a familiar mechanism: falling prices force leveraged holders to sell, which pushes prices lower still, which forces more selling. At the margin, the question of who absorbs new issuance matters as much as the rate decision itself. The US Treasury continues to issue at historically high volumes; a market that doubts its own capacity to absorb that supply sells before the next auction rather than after.

The half-point monthly move is the number that demands explanation. It is large enough to tighten financial conditions materially — mortgage rates, corporate borrowing costs and emerging-market dollar debt all move with the ten-year. What remains open is whether the PCE softness eventually reasserts itself, or whether the growth data has already set the floor for where yields settle.