UK government borrowing costs jumped to a two-month high and the pound weakened after John Healey was appointed Chancellor of the Exchequer in a surprise move by new Prime Minister Andy Burnham. The yield on 10-year gilts rose eight basis points to 5.049%, its highest in around two months, while sterling slipped 0.29% to 1.341 against the US dollar. The FTSE 100 closed 0.71% lower at 10,524.76 points. Analysts cited investor uncertainty over Burnham's economic policy, despite his pledge to stick to existing fiscal rules and fully fund new spending. Healey takes over from Rachel Reeves and faces weak growth, elevated borrowing, and high national debt, with key inflation and borrowing data due this week.