Countries with large debt burdens—France, Italy, the U.K., Japan—have come under the heaviest pressure in recent months as global debt surpasses $350 trillion, or about 305% of global GDP. Advanced economies are expected to borrow $18 trillion this year, competing with U.S. tech stocks and bonds for investor demand. While U.S. 10-year Treasury yields rose about 0.2 percentage point since June, France’s and Italy’s benchmark yields increased roughly half a point.

Inflation worries, fueled by the war in Iran and rising natural gas prices in Europe, have revived fears of sustained price pressures. The European Central Bank faces renewed pressure to hike rates, with investors pricing in 1.5 rate increases this year. Political instability in France, including President Emmanuel Macron’s spending challenges and Marine Le Pen’s rising poll numbers, adds to bond market anxiety.

Bond vigilantes are testing which sovereigns will yield first under pressure, as pension funds and insurers retreat from buying government debt in many countries.