Citigroup, a major US bank, made a significant “fat finger” error by mistakenly crediting a client’s account with $81 trillion instead of the intended $280. The error, which could have been one of the largest such blunders in banking history, was detected and reversed 90 minutes after it was posted by a third employee. This misentry would have been large enough to cover the entire US stock market at a significant premium, as the market’s valuation stood at $62 trillion at the end of 2022. No funds left the bank, and Citigroup informed both the Federal Reserve and the Office of the Comptroller of the Currency about the incident. The bank’s spokesperson stated that their detective and preventative controls promptly identified and reversed the error, emphasizing their efforts to automate controls and reduce manual processes. This incident follows another fat finger error in 2020 where Citi mistakenly sent $900 million to Revlon’s creditors, leading to legal battles and the eventual loss of money.

Source: https://www.theguardian.com/business/2025/feb/28/citigroup-credited-client-account-with-81tn-before-error-spotted