London CNN  —  UK regulators slapped a combined £62 million ($79 million) fine on Citigroup Wednesday for failures in its trading systems that almost resulted in stocks worth $189 billion being dumped onto European markets. The Financial Conduct Authority (FCA) imposed a fine of nearly £28 million ($36 million) on Citigroup (C), while the Bank of England’s Prudential Regulation Authority (PRA) fined it almost £34 million ($43 million) following investigations into the US bank, according to statements from the authorities. The regulators reduced their fines by 30% because Citigroup agreed to settle the matter. Without that discount, the combined fine would have topped £88 million ($112 million). The Bank of England highlighted an incident in May 2022 when one of the bank’s “experienced” traders sold $1.4 billion worth of stocks on European exchanges in error. In its statement, the FCA said the unnamed trader had intended to sell stocks worth only $58 million, but made an “inputting error,” which resulted in an order to sell $444 billion. Citigroup’s systems blocked $255 billion of that, meaning that $189 billion was sent to its trading platform for sale “over the rest of the day.” In total, $1.4 billion worth of stocks was sold before the trader canceled the transaction. Following the incident, Citigroup has taken steps to “improve and strengthen” the security of its trading systems, the central bank said. “Firms involved in trading must have effective controls in place in order to manage the risks involved. (Citigroup) failed to meet the standards we expect in this area, resulting in today’s fine,” said Sam Woods, deputy governor and chief executive officer of the PRA.