Global bond markets face relentless rise in yields despite intervention efforts

Despite attempts by Washington and Tokyo to stabilise markets, government borrowing costs continue to surge across major economies, signalling a fundamental shift in investor sentiment and raising concerns over fiscal stability and household finances.

Attempts by Washington and Tokyo to steady markets have so far done little more than interrupt a broader climb in government borrowing costs, with investors continuing to demand yields not seen for years across the US, UK, Germany and Japan. Reuters reported on 1 September that Japan’s 10-year yield had touched 3% for the first time since 1996, while the US 10-year Treasury was near 4.8%, Germany’s 10-year Bund reached 3.35% and Britain’s 10-year gilt rose to 5.25%, its highest since 2008. The move has persisted despite a surprise US Treasury buyback plan in August and a rare joint US-Japan currency intervention.

That matters well beyond trading desks. As the Associated Press noted this week, higher bond yields feed through into mortgages, car finance and the returns households receive on savings. In the US, the 10-year Treasury, which heavily influences mortgage pricing, reached 4.80% on 1 September, while the five-year Treasury, a benchmark for car loans, touched 4.55%, its highest since October 2025. Rising yields are also one of the few market forces that can rapidly alter political calculations because they raise the cost of servicing public debt.

The clearest sign of official concern came on 19 August, when the US Treasury said it would double buybacks of longer-dated debt from $2bn to at least $4bn per operation. According to Reuters, the larger operations will cover the 10-year to 20-year and 20-year to 30-year sectors from 9 September to 4 November. The announcement knocked the 30-year yield down from a 19-year high of 5.34% to about 5.18% on the day. Rene Albrecht of DZ Bank told Reuters policymakers feared the pain of yields at 5% or above at the long end because they would raise borrowing costs for both the state and the private sector.

But the respite was brief. By the following day, Reuters said the 10-year Treasury yield had climbed back to 4.70% and the 30-year yield to 5.249%, underscoring investors’ view that the buybacks addressed market plumbing rather than the underlying problem. Treasury Secretary Scott Bessent told CNBC he could increase the programme again and said the aim was to support liquidity in a thinly traded August market competing with heavy corporate issuance, including borrowing linked to AI infrastructure. Even so, analysts told Reuters that a $4bn operation was tiny in a $32tn Treasury market. Luis Alvarado of Wells Fargo Investment Institute called it “short-term relief”, while Michael Goosay of Principal Asset Management said intervention in the long end typically does not work well over time.

Japan’s currency market tells a similar story. Reuters reported in late June that the yen had weakened to 162.27 per dollar, a 40-year low, and was heading for a fourth straight quarterly decline as the gap between US and Japanese interest rates widened. After that slide, Tokyo and Washington carried out a rare joint yen-buying intervention on 1 August, the first such operation since 2011. Reuters later said Japan may have spent as much as $36.58bn, with the US Treasury selling euros to buy yen and the operation supported by a Federal Reserve liquidity backstop created during the pandemic. Finance minister Satsuki Katayama said: “We will not hesitate conducting further coordinated intervention.” The yen strengthened to 155.20 after the move, but the episode showed how rising US yields were spilling into other markets.

Inflation fears have given investors another reason to push yields higher. The Associated Press said renewed fighting in the Middle East had sent oil prices up, reviving worries that inflation could remain stubborn. The Guardian reported Brent crude had moved back above $90 a barrel after the US and Iran resumed direct attacks, while Reuters said euro area inflation rose above 3% in August, reinforcing expectations of a European Central Bank rate rise. In the US, Federal Reserve chair Kevin Warsh signalled at Jackson Hole that rates may still need to rise if inflation does not cool, and markets in the UK are now pricing in three quarter-point increases over the next year, according to the Guardian.

Behind the immediate volatility sits a bigger fiscal question. The Guardian said total US government debt has passed $40tn and annual deficits are forecast at about 6% of GDP for the foreseeable future. The Associated Press, citing the Congressional Budget Office, said this year’s federal deficit is expected to exceed $2tn, also roughly 6% of the economy, an unusually high figure outside recessions or wars. Neil Shearing of Capital Economics told the Guardian there had been “a recalibration” in how markets view US public finances, adding: “There’s no plan.” Russell Jones of Llewellyn Consulting made the same point more starkly, warning that markets often delay judgement until “they suddenly decide that that’s enough.”

There is also more competition for investors’ money than there was in the years after the financial crisis. Reuters and the Associated Press both pointed to heavy borrowing by large technology groups to finance AI data centres. The Guardian said Vanguard had calculated that five major tech companies issued $135bn of debt this year, up from an average of $35bn between 2020 and 2024. Reuters reported that Bessent himself cited competition from corporate issuance tied to AI infrastructure when explaining why the Treasury stepped in. That mix of bigger government deficits, revived inflation concerns and a private-sector borrowing surge helps explain why long-term yields have stayed elevated even after official intervention.

If this persists, the consequences will land in budgets and households alike. The Guardian said that in the UK, £1 in every £12 of public spending already goes on debt interest, with higher gilt yields likely to complicate the Treasury’s sums ahead of the autumn Budget. The same article quoted the National Institute of Economic and Social Research’s David Aikman saying governments were now more vulnerable simply because debt stocks were already so large. His warning was that policymakers are not replaying 2008, but they are entering a world in which the price of money is being reset upward and where markets are showing far less patience with fiscal drift.