A recent incident at US bank Citigroup highlights the potential risks associated with computer errors, also known as “fat finger” mistakes. The bank incorrectly credited a client’s account with $81 trillion (£64 trillion) instead of sending $280 million. This error was only discovered after two employees missed it and a third employee rectified it 90 minutes later.
The mistake would have been extremely large, equivalent to the entire US stock market value at over 1,200 times its current valuation. It also exceeds Elon Musk’s net worth by more than 200 times. Fortunately, no funds left the bank due to the swift detection and reversal of the error by Citigroup’s internal controls.
This incident underscores Citigroup’s efforts to automate and eliminate manual processes in their systems. The bank has faced similar issues in the past, including a $900 million Revlon payment mistake that took two years to recover from and led to the departure of its CEO.
Source: https://www.theguardian.com/business/2025/feb/28/citigroup-credited-client-account-with-81tn-before-error-spotted