For an excellent few hours on April ninth, catastrophe beckoned. Share costs had been falling for weeks. Then the marketplace for American Treasury bonds—usually among the many most secure property out there—began convulsing, too. The yield on ten-year Treasuries leapt to 4.5% (see chart 1), up from 3.9% days earlier. That meant bond costs, which transfer inversely to yields, had cratered. The failure of each dangerous and supposedly secure property without delay threatened to destabilise the monetary system itself.
