Citigroup recently dodged what could have been one of the most colossal banking errors in history when it mistakenly credited a client’s account with $81 trillion instead of the intended $280.
The staggering “fat finger” error—a term for when incorrect numbers are entered into a computer system—went unnoticed by two employees before a third finally spotted and corrected it 90 minutes after the transaction was posted, according to a Financial Times report. Fortunately, no funds left the bank during this period.
Citigroup Averts $81 Trillion Disaster
Following the incident, Citigroup disclosed the “near miss” to U.S. regulatory authorities, including the Federal Reserve and the Office of the Comptroller of the Currency.
To put the magnitude of this error into perspective, $81 trillion exceeds the entire value of the U.S. stock market, which stood at approximately $62 trillion at the end of 2024.Â
The sum would have been sufficient to purchase Elon Musk’s entire fortune—valued at $343 billion according to Bloomberg’s billionaires index—more than 200 times over. It also represents nearly one-fifth of the total global wealth, estimated by UBS last year to be around $450 trillion.
A Citigroup spokesperson addressed the incident, stating: “Despite the fact that a payment of this size could not actually have been executed, our detective controls promptly identified the inputting error between two Citi ledger accounts and we reversed the entry.Â
Our preventative controls would have also stopped any funds leaving the bank.”
The spokesperson emphasized that while there was no impact on either the bank or its client, “the episode underscores our continued efforts to continue eliminating manual processes and automating controls through our transformation.”
Banking Errors: Citigroup’s Troubled Track Record
This isn’t the first time Citigroup has encountered problems related to transaction errors. In 2020, the bank accidentally transferred $900 million to creditors of cosmetics company Revlon.Â
The mistake resulted in prolonged legal battles spanning two years as the bank attempted to recover funds from several hedge funds. The controversy contributed to the departure of then-Citigroup CEO Michael Corbat.
More recently, Citigroup faced a £61.6 million fine in the UK after a trader inadvertently sold shares worth $1.4 billion instead of the intended $58 million in May 2022. This error triggered a “flash crash” in European stock markets.
 According to reports, the trader had scrolled past error messages without reading them. The Financial Times report also revealed that Citigroup experienced 10 near misses exceeding $1 billion last year alone, citing an internal report.
Banking errors of this magnitude, while rare, have occurred elsewhere. In 2014, a Japanese trader canceled orders for 42 Japanese companies’ shares amounting to 67.78 trillion yen (£380 billion) before they were executed.
Economists point out that although the current banking processes have many processes to avoid such disasters, the growing sophistication of foreign financial dealings and the persistence of human monitoring in certain processes make the occurrence of “fat finger” events not a thing of the past.
As banks grow more mechanized, reducing the number of manual interventions will be the key to preventing these costly mistakes.
Citigroup’s latest $81 trillion blunder is a sad reminder of just how vulnerable even the world’s largest financial players are to simply human error—and the role multi-level verification systems play in avoiding it from occurring.
