TOKYO/LONDON/SINGAPORE (Sept 1): A sell-off in global bond markets deepened on Tuesday, the latest manifestation of investor angst about inflation and government debt levels that could bring ​fresh pain for consumers and businesses.

Japan's 10-year yield hit 3% for the first time since 1996 as the rout took in major economies from the US to ‌Germany and Britain.

Some of the world's leading economies, including the US, have seen their debt load rise sharply in recent years, while wars from Russia-Ukraine to the Middle East have sent oil and gas prices higher, adding to pressure on interest rates and the cost of living.

A deluge of bond sales from big tech companies aggressively raising money to fund the AI boom is adding to the pressure on bonds, just as the US government debt load has passed US$40 trillion.

Governments are jittery. ​Last month, the US Treasury stepped into markets in a bid to cap a rise in borrowing costs, which can spill over to higher loan rates for everything from household mortgages to business ​loans. Yields on 30-year Treasuries are close to the highest in 19 years. Yields rise when bond prices fall.

"Many developed markets have seen their long-term funding costs ⁠rise, as borrowing needs from both the public and private sectors have increased," said HSBC chief Asia economist Frederic Neumann.

Here are some related stories on the surge in government bond yields, what's behind them ​and why investors and borrowers are worrying:

The scale of the global shift is underscored by the rise in 10-year Japanese government bond (JGB) yields to 3% for the first time in 30 years, something seen as practically unthinkable until recently after over a decade of massive central bank debt purchases kept rates artificially low.

"The stalemate in the Middle East risks pushing energy prices higher...meanwhile, few actions have been taken to consolidate fiscal deficits in both economies," Tai Hui, ​the Asia-Pacific chief market strategist at JPMorgan Asset Management, said of the move in US and Japanese yields.

Brent crude rose nearly 2% to over US$92 a barrel on Tuesday and European natural gas prices were at their highest since ​March, after Monday saw the first exchange of direct attacks between the US and Iran in a month.

For Japan in particular, higher yields increase the cost of servicing the developed world's biggest debt pile at a time ‌when Prime Minister ⁠Sanae Takaichi is planning aggressive investment.

US 10-year Treasury yields pushed to the highest since January 2025 at 4.798%, while the 30-year yield was at 5.27% just six basis points shy of levels before August's intervention.

US Treasury Secretary Scott Bessent says that worries about rising debt and yields overlook the strength of the US economy.

Germany's 10-year yield was at 3.35%, its highest since 2011, as data showed eurozone inflation rose above 3% in August, cementing bets on a September European Central Bank rate rise, while Britain's 10-year gilt yield rose to 5.25%, its highest since 2008.

British and eurozone yields hit fresh over-10-year highs as the Middle East crisis stoked price ​pressures globally, driving market bets that central banks will ​raise interest rates soon.

Analysts noted ⁠some different forces at play as global borrowing costs rise.

"In Europe and the UK it is more because of heightened inflation expectations, while in the US the upticks in long-end yields are still more driven by higher real yields, although inflation expectations have been creeping up too," said Frances Cheung, OCBC's head of FX ​and rates strategy.

Real yields are the returns that a bond investor demands above inflation, an indicator of true borrowing costs for governments and companies, and ​can be affected by several factors, ⁠including long-run economic growth.

Bessent also shrugged off worries about the bond market in an interview with Reuters on Sunday, saying the effect of higher energy prices would fade.

Michiel Tukker, a senior rates analyst at ING, said economic growth combined with higher deficits and bond sales are pushing up real yields.

"There's no easy turnaround...and if you ask who will take the other side of this trade (i.e. betting yields will fall), that's difficult to see," he said.

And the global ⁠story can become ​self-reinforcing, since higher yields in one market can push them up elsewhere.

Australian 10-year yields notched their sharpest rise in five months ​on Tuesday, in part due to fears higher JGB yields would mean fewer Japanese buyers of Australian debt.

Further Japanese yield rises could drive a gradual re-allocation into Japanese assets, said TD Securities senior rates strategist Prashant Newnaha.

"It's a genuine regime change. JGBs were the ​anchor for global fixed income for a long time," he said.

"Now it has flipped."

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