Gilt Yields Hit 28-Year High Amid Starmer Political Turmoil

UK government bond yields reached their highest levels in 28 years on May 12, 2026, as financial markets reacted to a deepening political crisis within the Labour government and escalating geopolitical tensions between the United States and Iran.

The volatility in the gilt markets was driven by a combination of domestic instability in Westminster and fears of a global energy shock, resulting in a significant spike in borrowing costs for the British government.

The yield on 30-year gilts surged 13 basis points on May 12 to reach 5.8 per cent, marking a multi-decade peak. Simultaneously, the UK 10-year yield spiked 10 basis points to hit 5.1 per cent.

These market movements coincided with a widening rebellion within the governing Labour Party. Nearly 80 Labour MPs have now called for the resignation of Prime Minister Sir Keir Starmer. The pressure on the Prime Minister intensified as four ministers resigned from their posts, and reports indicated that numerous other cabinet members were expected to call for a formal timetable for his exit.

The instability in the UK’s political leadership created a climate of uncertainty that weighed heavily on investor confidence. Neil Wilson, a UK investor strategist at Saxo Market, warned that the situation could deteriorate further if the leadership struggle becomes more aggressive.

“We could see a blowout in longer-dated gilts if this turns into a dogfight – political, fiscal and inflationary risks will rise. Markets tend to dislike a lack of certainty over who runs a government.”Neil Wilson, UK investor strategist at Saxo Market

While domestic turmoil provided the primary catalyst for the bond market volatility, external geopolitical pressures added further strain. Tensions in the Iran war escalated following comments from Donald Trump regarding a month-long ceasefire between the U.S. And Iran.

On May 11, 2026, Trump described the ceasefire as being on "massive life support." He further criticized a counter-proposal from Iran aimed at re-opening the Strait of Hormuz, labeling the proposal "totally unacceptable" and a "piece of garbage."

Tehran defended its position through Esmail Baghaei, the spokesperson for Iran’s foreign ministry, who stated that the proposals put forward by Iran were "responsible" and "generous."

The diplomatic friction triggered immediate reactions in the energy markets, raising concerns over a potential energy shock. Brent crude, the international benchmark for oil prices, rose 2.5 per cent to $106.

The combined impact of the political instability in London and the rising cost of energy weighed on the UK’s equity markets. The FTSE 100 sank one per cent following the latest developments in the bond and oil markets.