Bithumb has won a second court ruling ordering a customer to hand back proceeds from bitcoin the exchange mistakenly paid out in February, strengthening its legal position as two related suits remain awaiting judgment.

The rulings come as Bithumb fights to recover the last of the money it mistakenly paid out, while smaller domestic rivals move to cut trading fees.

Why Bithumb is taking customers to court

Judge Kim Yu-seong, a single-judge civil court judge in the Seoul Central District Court's Civil Division 90, sided with Bithumb in an unjust enrichment claim against a user identified only as A. The disputed sum in the case is 194,000,443 won, the second-largest of the four claims Bithumb filed. Unjust enrichment is a standard remedy under the Korean Civil Code, which obliges a person who has gained a benefit without legal grounds to return it.

A day earlier, on Aug. 26, the same court ruled in favor of Bithumb in a separate suit worth 4,989,990 won. Both cases were handled through public notice service, a procedure courts use to deem documents served by posting them when a defendant's address or workplace cannot be found. Under the Civil Procedure Act, such service takes effect two weeks after posting whether or not the defendant ever sees the documents, so a case can be decided without any response from the other side. Both are first-instance rulings that the defendants retain the right to appeal.

Bithumb's back-to-back wins set a favorable precedent for the two suits still undecided, with claims of 500 million won and 14.8 million won outstanding.

The lawsuits stem from an incident in February, when a Bithumb employee processing a customer event reward entered bitcoin as the payout unit instead of won. The mistake credited users with 620,000 units of BTC — a figure Cryptopolitan reported was worth around $43 billion at the time, far beyond what the exchange actually held and nearly 3% of bitcoin's 21-million-coin maximum supply.

Financial authorities said Bithumb froze transactions and withdrawals once it caught the error and managed to recover 618,214 units, but 1,786 BTC had already been sold.

Bithumb has been pursuing those funds separately. By March 10, it told the National Assembly it had clawed back 99% of the 1,788 units still outstanding at that point. In the same month, it took four users who had sold the coins and kept the cash to court.

Market and regulatory fallout

Following the payout incident, the Financial Services Commission (FSC) proposed requiring every exchange to run an always-on reconciliation system that checks user ledgers against actual holdings every five minutes, alongside automated verification and multi-approval steps for manual transactions such as event rewards.

Cryptopolitan reported that Bithumb had previously faced a 36.8 billion won fine (about $25 million) and a six-month partial suspension over separate identity-verification failures. The exchange paused its suspension on May 1, allowing it to keep operating until it receives a final ruling.

Local competition intensifies

Meanwhile, Bithumb's smaller competitors are scrapping their trading fees. Coinone eliminated fees across all listed cryptocurrencies and offered a renewable 30-day zero-fee voucher. Digital X, which runs Korbit, also waived fees in its won market for an entire year ending Aug. 24, 2027.

Mirae Asset Consulting recently took control of Korbit after buying more than 97% of it, and Korea Investment & Securities holds a 20% stake in Coinone.

Trading commissions are the main revenue line for South Korea's won-based exchanges, so the fee waivers forgo that income even as the platforms compete for trading share. Coinone and Korbit still trail far behind Bithumb in volume, with Coinone at 2.39% of won-based volume this month and Korbit at 0.52%, against Upbit's 68.11% and Bithumb's 28.95%.

Bithumb's 24-hour volume topped 2 trillion won last Saturday as bitcoin briefly cleared $80,000. Bitcoin's rally has ignited hope that the company will be able to revive its fee revenue after operating profit for the first half of the year fell 83.4% at Bithumb.