Bithumb wins $140,000 lawsuit over 620,000 BTC fat-finger error

A Seoul court ruled for Bithumb in a 194 million won ($140,000) unjust enrichment suit, the exchange's second win in four civil cases tied to a February error that credited 620,000 BTC to users.

Judge Kim Yu-seong of the Seoul Central District Court's Civil Division 90 issued the ruling on Aug. 27, ordering the user to return proceeds from selling the mistakenly credited bitcoin, according to local news outlet Digital Asset. Financial Supervisory Service Governor Lee Chan-jin had publicly characterized the affected balances as unjust enrichment subject to restitution.

The ruling covers the second-largest of four claims Bithumb filed in March against users who sold the mistakenly credited bitcoin and kept the proceeds. The remaining claims are valued at about 500 million won ($361,000), 14.8 million won ($10,700), and 5 million won ($3,600). The court also ruled for Bithumb on Aug. 26 in the smallest case, worth about 4.99 million won.

The back-to-back rulings establish precedent for the two pending cases and reinforce that mistakenly credited crypto carries the same restitution duty as mistaken fiat transfers under South Korean law. Bithumb, which targets an initial public offering in 2028, still faces two unresolved claims and remains under regulatory scrutiny following the February incident.

The dispute traces to Feb. 6, when Bithumb was running a promotional random-box campaign distributing won-denominated rewards between 2,000 won and 50,000 won per winner. A staff member entered the payout unit as bitcoin instead of won, crediting approximately 620,000 BTC — then worth about $43 billion — across roughly 695 user accounts.

The phantom balances exceeded Bithumb's actual bitcoin reserves, which were estimated at around 40,000 BTC at the time. The exchange blocked trading and withdrawals on affected accounts within about 40 minutes and recovered 618,214 units before they were traded. But 1,786 units had already been sold, and Bithumb filed separate lawsuits in March against four users who did not return the proceeds.

The incident briefly caused the BTC-KRW pair on the platform to plunge about 15 percent, and South Korean authorities launched an investigation into Bithumb citing a lack of internal controls and risk management. The Financial Services Commission subsequently required all exchanges to build systems that continuously reconcile user ledgers against actual holdings of virtual assets at five-minute intervals. The Bank of Korea has also floated the idea of a crypto circuit breaker, citing the Bithumb episode as an example of how a single input mistake can distort local price discovery.

Bithumb reported to the National Assembly that as of March 10 it had recovered 99 percent of the 1,786 bitcoin sold before its account freeze took effect. In April, the exchange filed for a provisional seizure targeting the remaining seven BTC that were still unreturned, valued at approximately 700 million won at the time of the original error.

What the verdicts mean for the remaining cases

Korean legal experts have consistently characterized such cases as unjust enrichment, meaning recipients are required to return the assets, and where the coins have already been sold, users may need to repurchase them at higher prevailing prices to make good. That exposure has widened as bitcoin traded well above the 100 million won mark in the months following the incident, up from the low 80 million won trough recorded during the February selloff.

For the broader industry, the ruling reinforces the principle that mistakenly credited crypto is likely to be treated the same way South Korean courts have historically treated mistaken fiat transfers, with a duty to return the value regardless of who caused the error.

For Bithumb, which is advancing its long-planned initial public offering and remains under an active regulatory rehabilitation program, closing the remaining courtroom exposures from the February incident removes another overhang from both its balance sheet and its supervisory record.

This article is for informational purposes only and does not constitute investment advice.