In late September 2026, the FT reported that oil prices and Treasury yields were moving in their tightest correlation in four decades, with the 10-year yield at its highest since 2007 and West Texas Intermediate spiking on the war in Iran. The discussion had settled on what that lockstep meant for government, corporate and household borrowing costs. That framing is now contested: the correlation broke apart in mid-September, when oil fell and yields kept rising. What drove the two apart, and whether the link re-forms, is open.