A trader at Citi mistyped a share order when he intended to sell $58 million worth of shares but accidentally entered a basket of 349 stocks with a notational value of $444 billion|Matt Buck|CC BY-SA 2.0

Citi agreed to pay £61.6 million ($79 million) to British regulators in fines over a trader’s typo that caused a sudden fall in European stocks in May 2022.

The trader mistyped a share order when he intended to sell $58 million worth of shares but accidentally entered a basket of 349 stocks with a notational value of $444 billion.

The Wall Street giant’s systems immediately fired off warnings. The trader canceled the order 15 minutes after punching it in, but $189 billion worth slipped through. As a result, about $1.4 billion worth of equities began to be sold across European exchanges.