UK borrowing costs march higher, sterling slumps as Starmer's future in doubt - Finance news and analysis from Global Banking & Finance Review
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UK borrowing costs march higher, sterling slumps as Starmer's future in doubt

Published by Global Banking & Finance Review

Posted on May 12, 2026

4 min read

· Last updated: May 12, 2026

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Long-term UK bond yields rise to 1998 high, sterling slumps as Starmer's future in doubt

Market Turmoil Amid Political Uncertainty

By Yoruk Bahceli

LONDON, May 12 (Reuters) - Long-term British borrowing costs surged to their highest in nearly 30 years, sterling slumped and shares fell on Tuesday as investors brace for a potential change of leadership that could weaken fiscal discipline.

Starmer Faces Mounting Pressure

Prime Minister Keir Starmer is under mounting pressure to resign after his governing Labour Party suffered big losses in last week's local elections, but he remained defiant on Tuesday at a cabinet meeting, telling ministers he would "get on with governing". Almost 80 of his lawmakers have called on him to go.

There has been no official move to trigger a leadership contest, Starmer said, and one of his ministers said no one had challenged the prime minister during the cabinet meeting.

Investor Concerns Over Fiscal Policy

That provided little respite to investors worried that a replacement would be more left-wing than Starmer and push for more spending at a time when UK finances are already stretched.

Punters on betting platform Polymarket now see a Starmer departure by the end of June as a coin toss, and the odds of him leaving by year-end have risen to 80% from around 70% before last week's elections.

UK borrowing costs remain the highest among the Group of Seven advanced economies and have risen the most since the Iran war as inflationary concerns prompted a dramatic shift in expectations from Bank of England rate cuts to rate hikes. Any further rise will add to pressure on the public finances.

Bond Yields Hit Record Highs

On Tuesday, 30-year yields, sensitive to fiscal risks, touched their highest since 1998 at 5.81%, rising as much as 14 basis points (bps).

The benchmark 10-year gilt yield rose to 5.13%, the highest since 2008.

"For many the writing is on the wall at this stage, it’s just a matter of how quickly (Starmer's) exit happens," said Jordan Rochester, head of fixed income, commodities and currencies strategy at Mizuho.

Market Reactions and Analyst Insights

Relief Bounce and Continued Volatility

RELIEF BOUNCE

Yields edged slightly lower on news the cabinet had not challenged Starmer, but were last up around 10 bps on the day.

"You're seeing a bit of a relief bounce... on the fact that the cabinet meeting seems to have passed with no one overtly challenging the PM," said Michael Brown, senior strategist at broker Pepperstone.

But the relief won't last, Brown said, adding: "When you look at gilts, when you look at the pound, it's probably going to get a lot worse before it gets better."

Sterling and Stock Market Impact

The pound dropped to as low as $1.3503 and was last down 0.5% in its biggest daily drop in over a month, against a broadly stronger dollar.

Investors see Starmer and his finance minister Rachel Reeves as most favourable to markets, particularly given Reeves' commitment to fiscal rules limiting borrowing.

"The bond market is reacting not only to Starmer’s potential departure, but also to who his successor could be, and to the prospect of a drawn-out leadership battle that leads to more fiscal promises that the UK cannot afford," said Kathleen Brooks, research director at broker XTB.

British banks also fell with Barclays, NatWest and Lloyds all falling over 3% each, leading declines among European banking stocks.

Analysts at JPMorgan said they now expected Britain's banking surcharge to rise to 5% from 3% as a leftward shift in policy is more likely.

Britain's broader stock market was down 0.4%.

European Bond Markets Under Pressure

Bond markets were also under pressure across Europe as hopes for a peace deal on Iran faded after U.S. President Donald Trump said a ceasefire was on "life support". This pushed traders to add to their rate hike bets.

Looking Ahead: Policy and Political Developments

Upcoming Legislative Agenda

Investors will have a chance to scrutinise Starmer's policy plans on Wednesday, when King Charles will read out the government's legislative agenda for the coming period at the formal State Opening of Parliament.

(Reporting by Yoruk Bahceli; editing by Dhara Ranasinghe and Gareth Jones)

Key Takeaways

  • Benchmark 10‑year gilt yields jumped ~11 bps to 5.11%, approaching highs of July 2008, driven by inflation fears from the Iran conflict and political uncertainty over Keir Starmer’s leadership. (moneyweek.com)
  • 30‑year gilt yields climbed ~10 bps to around 5.78%, the highest since 1998, intensifying concerns over long‑term borrowing costs amid fiscal credibility risks. (moneyweek.com)
  • Sterling weakened roughly 0.5% to about $1.354 and fell against the euro; equity markets fell with the FTSE 100 dropping near 1% as investor anxiety mounts over potential changes to fiscal stewardship under Starmer. (moneyweek.com)

References

Frequently Asked Questions

Why are UK borrowing costs rising?
UK borrowing costs are rising due to concerns over fiscal stability amid uncertainty about Keir Starmer's leadership and recent government turmoil.
What are investors expecting regarding UK leadership?
Investors are bracing for a potential change in leadership as Keir Starmer faces calls to resign following election setbacks.
Which market sectors were most affected by the uncertainty?
Banking stocks were notably affected, with Barclays, Natwest, and Lloyds seeing significant declines in share prices.

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