The US bond market was in something close to pandemonium last week. A sharp sell-off in long-dated Treasuries sent yields shooting higher, triggering alarm across markets. Washington stepped in with an announcement that it would ramp up buybacks of longer-dated bonds, briefly calming nerves and pulling yields down. But the relief did not last. Yields soon began climbing again, underlining the market's deeper anxiety over who will absorb America's rapidly growing debt pile-and how much return investors will demand to do so. The concern is not unwarranted. US government debt has crossed $40 trillion, while the fiscal deficit remains large. Interest payments are approaching $1.2 trillion a year. At the same time, companies-particularly those building Al infrastructure and data centres-are raising large amounts of debt and competing with the Treasury for capital.