The North American bank Citigroup made a huge mistake by temporarily crediting US$81 billion to a customer’s account, when the intended transaction was only US$280. The mistake, which went unnoticed by two employees, was detected by a third around 90 minutes later and reversed a few hours later, without any money leaving the bank.
Error detected and corrective measures
According to the Financial Times, cited by CBS News, the mistake was identified by a third bank employee, who alerted to the discrepancy. Citigroup reported the incident to the United States Federal Reserve and the Office of the Comptroller of the Currency, ensuring that its preventive controls would also have prevented the undue amount from leaving.
A bank spokesperson confirmed, in statements reproduced by CBS News and Business Insider, that the error occurred during a transaction between Citi’s own internal accounts. According to the same statement, “although a payment of this size could not have actually been executed, our controls promptly identified the error and reversed the entry”, adding that the preventive mechanisms would also have prevented funds from leaving the bank.
The incident has once again exposed the operational weaknesses of a large financial institution that remains under regulatory scrutiny as it attempts to automate processes and reduce reliance on manual procedures. Even so, the bank guaranteed that there was no impact on the customer or the institution.
What would have happened if the money had come in and become available?
If the amount had entered and remained available in the customer’s account by mistake, this would not mean that it automatically belonged to him.
In the United States, official banking consumer protection sources, such as the OCC and the CFPB, explain that, when a deposit is credited in error, the bank can correct it and withdraw the funds without needing authorization from the holder. If the money has already been transferred, the institution can demand a refund and take legal action.
In legal terms, the logic also involves the idea of unjust enrichment, widely recognized in North American law: whoever receives a benefit without a legitimate basis may have to repay it.
There are real cases that show the risk of using money received in error. One of the best known occurred in Pennsylvania, when a couple spent around 120 thousand dollars that had been deposited in their account in error. According to CBS News, Business Insider and the local North American press, the two were accused of theft and receiving stolen property and ended up, in 2020, sentenced to probation and community service.
A mistake that wasn’t the first
Although this incident was resolved before any outflow of funds, it was not the first time Citigroup faced a similar issue.
In 2020, the bank mistakenly transferred around $900 million to Revlon’s creditors, in a case that led to more than two years of litigation. According to Reuters, a substantial part of the amount remained in dispute for months, until the appeal and a subsequent agreement brought the process to an end in 2022.
According to the Financial Times, cited by Reuters and other financial media, Citigroup recorded 10 near misses of a billion dollars or more in 2024, down from 13 the previous year.
Impact on the banking sector
A mistake of this size, even corrected in time, can affect the bank’s perception of trustworthiness among customers, investors and regulators.
The Citigroup case was not isolated, but it demonstrates how operational lapses, even when they are stopped before producing actual losses, can expose relevant internal vulnerabilities.
According to Reuters and the OCC, US regulators maintain pressure on Citi to strengthen risk control, data quality and internal processes. In 2024, the bank was even targeted with a new fine of 136 million dollars for insufficient progress in correcting flaws already identified.
And in Portugal?
In Portugal, the legal logic goes in the same direction, although with a different legal basis. According to article 473 of the Civil Code, in the regime of unjust enrichment, whoever receives an amount unduly is obliged to repay what they unjustly received.
This means that, even if the money enters the account by mistake and without any intervention from the holder, this amount does not automatically become yours. If the return is not made voluntarily, the bank or injured entity can go to court to recover the amount.
Depending on the specific facts, criminal liability may even be imposed if there is intentional misappropriation of the amount received. But, on a civil level, the basic rule is clear: receiving money by mistake does not create a legitimate right to keep it.
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