Britain's government borrowing costs remained elevated as political turmoil over a leadership challenge to Prime Minister Keir Starmer continued to unsettle the bond market. Yields on UK 10-year gilts have climbed back toward 5%, leaving the country with the highest long-term borrowing costs in the Group of Seven advanced economies.
The jitters center on Andy Burnham, the mayor of Greater Manchester, who has positioned himself as the front-runner to replace Starmer at the helm of the governing Labour Party. Burnham's path back to Westminster, and to any leadership bid, hinges on winning the June 18 by-election in Makerfield, in north-west England, which would secure him a seat in the House of Commons.
Investors have grown wary that a Burnham-led government would tack to the left of Starmer and his finance minister, Rachel Reeves, and ramp up public borrowing. That concern has rippled through the market for gilts, as UK government bonds are known, with sell-offs in recent weeks pushing yields to multi-decade highs before easing somewhat.
Burnham abruptly cancelled a call intended to placate nervous investors, according to reports, declining an opportunity to reassure the market about his potential policy mix. The move did little to calm sentiment among holders of UK sovereign debt, many of whom have appeared supportive of Reeves and Starmer remaining in their roles given their stated commitment to fiscal discipline.
Gilt yields have also tracked moves in U.S. Treasurys, which have risen on expectations of tighter monetary policy after strong American jobs data. The combination of domestic political risk and global rate pressure has kept UK borrowing costs stubbornly high.
On monetary policy, markets are pricing in close to two Bank of England interest-rate increases this year, with the first move seen as likely in September. Higher rates would add to the government's debt-servicing costs at a time when the fiscal outlook is already under strain.
The standoff has placed the gilt market at the center of British politics, with the price of government debt serving as a real-time barometer of investor confidence in the country's leadership and economic direction. Starmer has said he will not step down, setting up a test of strength that could be decided in part by the Makerfield result.
For now, traders are watching the June 18 by-election closely, aware that the outcome could either defuse the immediate uncertainty or open a new and more volatile chapter for UK assets.