US long-term government bonds were hit with a fresh wave of selling on Thursday as US Treasury secretary Scott Bessent’s intervention to prop up the market failed to soothe investor jitters.The yield on 30-year Treasury bonds was up as much as 0.07 percentage points at 5.27 per cent in New York morning trading on Thursday, reversing most of the 0.09 percentage point fall that followed the Treasury announcement on Wednesday, before dipping to 5.25 per cent. Bond yields move inversely to prices.The Treasury said on Wednesday it would “at least double” its purchases of securities maturing in 10 to 30 years, increasing such operations from $2 billion to “at least” $4 billion.“We don’t think this [intervention] can succeed, in isolation,” said Eoin Walsh, portfolio manager at TwentyFour Asset Management. “Interventions such as this look like a sticking plaster.”Other global bonds also sold off. The yield on 30-year UK bonds rose 0.02 percentage points to 5.81 per cent after falling 0.05 percentage points on Wednesday.[ Why government debt matters: bond investors, yields and their impact on the economyOpens in new window ]The US dollar, which fell sharply following Wednesday’s announcement, continued its slide on Thursday. An index of the dollar’s value against a basket of its peers fell as much as 0.3 per cent after a 0.8 per cent fall on Wednesday. It later recovered about half of Thursday’s early losses to trade down 0.1 per cent.The selling on Thursday underscores the deep concern among investors over the US’s mounting public debt burden and whether policymakers will be able to contain the eruption of inflation triggered by US president Donald Trump’s war in Iran. Those concerns have particularly weighed on longer-term debt in recent months, with the 30-year yield climbing from 4.9 per cent at the end of June.Wall Street analysts, many of whom were surprised by the Treasury buyback plan, said the move was unlikely to be large enough to offset investor concerns.“Without a shift to fiscal consolidation – higher taxes, [a] slower pace of government spending or outright declines in government spending as happened in the 1990s – the buy-backs will prove to be only temporary,” said Joe Brusuelas, chief economist at professional services firm RSM US.Bessent told CNBC on Thursday there was “a very good chance” that the US would begin to lower its fiscal deficit.“We believe the yields don’t reflect the underlying fundamentals,” he said. “We believe that the liquidity, especially at the 30-year point, is very poor.”Bessent also reiterated that the Treasury’s buy-backs “could be more than $4 billion per issue”, in line with Wednesday’s announcement.The US national debt reached a record $40 trillion on Tuesday, according to Treasury department data. The government has consistently run deficits of 6 per cent of GDP in recent years and is not expected to reduce them any time soon, owing to Trump’s tax cuts and pledge to raise defence spending by more than 50 per cent to $1.5 trillion a year.Analysts at MUFG said there was a sense that the unscheduled announcement by the US Treasury was “lacking a strategic plan”. “The danger now following this announcement ... is that it proves counterproductive and leads to reduced appetite for either holding US assets or reduced appetite for exposure to the US dollar or both,” they said.They added that Bessent was not following his own advice to focus on policy rather than market signalling by failing to reduce the US fiscal deficit through fiscal consolidation.Keith Patton, head of global rates and unconstrained fixed income at Columbia Threadneedle Investments, said the plan announced by Bessent was “minuscule” compared with the Fed’s successful quantitative easing programmes.“Such interventions only work if they are followed up with key policy initiatives, especially around spending,” he said. Lower spending was not expected for the “foreseeable future”, he added.Kit Juckes, global head of foreign exchange strategy at Société Générale, said it was “up for debate” whether the Treasury’s announcement would hold yields down.“As the US publicly held debt level reaches 100 per cent [of] GDP and budget deficits remain high”, the willingness of foreign investors to buy US assets “will be a growing issue”, he said.He added that this would “either force the US to tighten fiscal policy, accept higher borrowing costs or let the dollar weaken. No prizes for guessing which solution the market now sees as most likely.” – Copyright The Financial Times Limited 2026