UK borrowing costs surge, narrowing fiscal space raises concerns

⑴ The yield on UK government bonds surged from 5.24% to 5.35% on Wednesday, marking the largest single-day increase in three weeks, and further broke above 5.38% on Thursday. Falling bond prices have driven up borrowing costs for the government, households, and businesses. ⑵ This round of volatility reflects both a global bond market sell-off and investor concerns about the UK’s fiscal plans. The 10-year government bond yield was below 5% prior to the incumbent prime minister taking office but has since touched its highest level since 2007. ⑶ The prime minister’s previous comments on the UK not relying excessively on the bond market have drawn attention. He recently reiterated this view, stating that the country is overly exposed to bond market risks. However, he is not advocating abandoning spending restraints but rather calling for a leaner and more efficient state. ⑷ Bond market volatility has already spread to mortgage rates, with the average two-year fixed rate rising to 5.92%, the highest since July 2024, and the five-year fixed rate reaching 5.96%, a level last seen in October 2023. ⑸ The rise in borrowing costs stems from investors expecting interest rates will need to be raised to curb inflation, with UK government bonds hit particularly hard due to market concerns over weakened fiscal discipline. ⑹ Official data shows debt interest payments reached £8.8 billion last month, setting an August record. In the first five months of this fiscal year, nearly £3 trillion of government bonds accumulated £50 billion in interest payments, equivalent to £327 million per day. ⑺ The surge in interest payments is putting pressure on the prime minister and chancellor ahead of next month’s budget, amid market concerns the government may be forced to increase borrowing or raise taxes. ⑻ Reports suggest the prime minister and chancellor may opt to reduce the fiscal buffer in order to limit tax increases and avoid spending cuts, possibly shrinking the buffer from £24 billion forecast in March to around £14 billion. ⑼ Analysts point out that with another sharp rise in government bond yields, market confidence in fiscal discipline may be undermined. If the government is unwilling to make tough decisions on welfare spending and other areas, it could signal deeper underlying problems. ⑽ The UK government’s current borrowing costs are the highest among the G7. Whether the budget can maintain a credible fiscal plan will be a key focus for the markets.