A Brief History of Wall Street’s Fat Finger Problem: QuickTake

A single Citigroup Inc. trader caused havoc in European stocks in 2022 after the simplest of blunders: The staffer entered the value of stocks they wanted to buy into the wrong field of the bank’s trading system. The mistake triggered a five-minute selloff in European stocks from France to Norway, with $1.4 billion worth of equities sold in error.

Citing a litany of control failures, UK regulators handed down a £62 million ($79 million) fine on May 22 that, together with the trading losses from that day in 2022, mean the erroneous trade cost the desk nearly two years of ...