Citigroup behind error that wiped out $315 billion from European markets

Citigroup’s London trading desk was a behind a flash crash that sent shares across Europe tumbling on Monday, dealing a fresh setback to the bank’s yearslong efforts to improve controls.

A trader at the US firm made a mistake “inputting a transaction,” Citigroup said late last night, after a knee-jerk selloff in Swedish stocks in five minutes wreaked havoc in bourses from Paris to Warsaw. The bank said it identified the error “within minutes” and corrected it.

The violent reaction saw the main European index lose as much as 3%, wiping out 300 billion euros ($315 billion) at one point. It revived