Belgian, French bond yields hit multi-decade highs

Belgium's 10-year government bond yield rose above 3.8 percent on August 18, reaching its highest level since the eurozone debt crisis of 2012, while France's equivalent yield climbed above 4.1 percent, a level not seen since June 2009. The moves reflect growing investor concern over fiscal sustainability in two of the eurozone's most indebted economies.tradingeconomics+1

Fiscal Vulnerabilities in Focus

Both countries carry debt-to-GDP ratios above 100 percent and deficits near or above 5 percent of GDP. France's public debt reached 117.5 percent of GDP in the first quarter of 2026, according to the statistics office INSEE, while Belgium's stood at 107.9 percent at the end of 2025. France closed 2025 with a deficit of 5.1 percent of GDP, or €152.5 billion, and Belgium's federal Monitoring Committee has projected its deficit rising toward 5.8 percent by 2029 without corrective measures.brusselssignal

The yield increases are part of a broader rise in eurozone long-term rates driven by higher energy prices, inflation concerns, and record government bond supply estimated at €930 billion in net issuance for 2026. Germany's 10-year Bund yield has also risen to roughly 3.25 percent, its highest since 2011. The European Central Bank flagged in its May 2026 Financial Stability Review that sovereign bond markets face "increasing pressure from rising yields, fiscal vulnerabilities and global spillovers."think.ing+2

Rising Borrowing Costs and Household Impact

Jean Deboutte, director of Belgium's Federal Debt Agency, told the news agency Belga that investors now fear prolonged high inflation and a firm central bank response. "Investors now fear high inflation for a long time, and a firm reaction from the central banks, which will raise their policy rates as a result of that inflation," he said.brusselssignal

The fiscal consequences are direct: Belgian federal interest costs reached €10.78 billion in 2025, with projections showing charges climbing by €11 billion between 2026 and 2031. France's 2026 budget puts its interest bill at €74 billion. For France, the pressure is compounded by political uncertainty ahead of the 2027 presidential election, with Fitch set to review its A+ rating on August 28.brusselssignal

Higher sovereign yields are also feeding through to household borrowing. In Belgium, the average 25-year fixed mortgage rate reached 4.13 percent in May, its highest in more than a decade. For a typical €300,000 loan, the total interest cost over the term can exceed that of a year earlier by more than €25,000. Reuters Thomson Reuters Corporation ↘ 0.33% reported in April that the broader European yield surge was "pushing up government borrowing costs and adding to the pressure on the continent's fragile public finances."reuters+1