Plans by Britain’s new prime minister, Liz Truss, to cut taxes and freeze energy bills landed like a bomb in a niche corner of financial markets, hitting government bond prices so hard that the Bank of England was compelled to intervene, and highlighting how obscure derivatives can still shake up the global financial system more than a decade after the 2008 financial crisis.On Wednesday, 30-year British government bonds swung more in a day than they had in a full year for the past five years — the biggest one-day move on record. In currency markets, the pound slumped to its lowest level on record against the U.S. dollar, coming close to parity, with moves of a magnitude comparable to the …
