A Seoul court ordered a defendant to repay approximately 194 million Korean won, equivalent to about $140,513, to Bithumb on August 27, the second victory the crypto exchange has secured in its civil recovery effort stemming from a catastrophic February data entry error. Digital Asset, the South Korean outlet that first reported the August 27 ruling, noted that the recent decisions raise the likelihood Bithumb will recover the remaining overpaid amounts through the courts.
Judge Kim Yu-seong of the 90th Civil Division of the Seoul Central District Court ruled in favor of Bithumb in the unjust enrichment lawsuit, which targeted a user who sold bitcoin the exchange had mistakenly credited and retained the cash proceeds.
One day earlier, on August 26, Bithumb had already won a separate case involving approximately 5 million won. The two rulings came from four civil lawsuits the exchange filed in March against users who received the wrongly distributed bitcoin and converted it to cash rather than return it. The largest pending case involves roughly 500 million won, approximately $362,229. A fourth case covers about 14.8 million won.
What a single wrong keystroke cost Bithumb
The incident happened in February when a staff member entered a promotional reward amount using BTC as the unit instead of KRW. The result was the accidental internal distribution of 620,000 bitcoin, worth approximately $43 billion at the time, to hundreds of users as part of a campaign giveaway. It was not a system breach. It was a human input error of the kind financial markets have a specific term for: a fat finger trade.
The BTC-KRW trading pair on Bithumb's platform plunged roughly 15% almost immediately. South Korean financial authorities launched an investigation into the exchange and cited a failure in internal controls and risk management. The National Assembly convened an unusual emergency inquiry through the Political Affairs Committee to address accountability, and legislators subsequently proposed a bill to prevent similar occurrences. Bithumb reported to the National Assembly that by March 10, it had recovered 99% of the 1,788 bitcoin that had not been immediately returned.
The broader history of fat finger disasters
Fat finger errors have caused market-level disruption far beyond crypto. The most referenced case in financial history remains Mizuho Securities in December 2005. A trader tried to sell one share of newly listed Japanese recruitment firm J-Com at 610,000 yen but accidentally entered an order to sell 610,000 shares at 1 yen each. The Tokyo Stock Exchange's systems could not cancel the order in time. The mistake cost Mizuho approximately 40.7 billion yen, the equivalent of roughly $347 million at the time, and exposed critical gaps in exchange-level error controls. Japanese regulators subsequently overhauled cancellation procedures.
A structurally similar case unfolded in South Korea in April 2018, when Samsung Securities accidentally issued 2.81 billion shares to employees instead of paying 2.81 billion won in dividends. The difference was the unit: shares rather than cash, worth approximately $98.6 billion rather than $2.63 million. Some employees sold portions of the shares before the error was caught. Samsung Securities stock dropped about 11% on the day, and the company faced regulatory sanctions and a suspension from certain operations.
In crypto markets, fat finger errors carry additional consequences because blockchain transactions are irreversible once confirmed and because thin order books on some platforms can amplify price moves dramatically. In 2021, a series of NFT-related fat finger sales saw assets listed for a fraction of their intended prices, with buyers completing purchases within seconds of the listings going live. In one widely reported case, a Bored Ape NFT sold for approximately $3,000 after the seller accidentally listed it for 1 ETH rather than 100 ETH.
What courts must decide when users keep the proceeds
The legal question in Bithumb's four lawsuits is not whether the error occurred but whether recipients who sold the mistakenly credited bitcoin and kept the money must return those proceeds. South Korean civil law on unjust enrichment requires a defendant to return gains they were not legally entitled to receive, regardless of whether they caused the error.
The August 27 ruling confirmed that framework applies here. The defendant in the 194 million won case received bitcoin through no legal entitlement and converted it to cash. The court found that cash must be returned to Bithumb. The same logic underpinned the 5 million won ruling the day before.
Bithumb's win in the two smaller cases strengthens its position in the remaining litigation, particularly the 500 million won claim, where the same unjust enrichment argument applies to a larger amount.
Gunel Ismayilova
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