Bithumb issued an official apology over a mass erroneous bitcoin (BTC) payout that occurred on Feb. 6. Bithumb made clear the incident was an error in its internal payout process, not a hack, and stressed the market has stabilised.

In a notice on Feb. 7, Bithumb said, "An abnormal amount of bitcoin was paid to some customers during the event payout process," adding, "We sincerely apologise for the inconvenience caused to customers due to the confusion."

According to Bithumb, the incident occurred while paying out prizes for a "Random Box" event. Instead of 2,000 won in cash, 2,000 BTC per person (about 192 billion won) was mistakenly deposited, and some accounts that received it immediately began selling, triggering a temporary sharp drop in the bitcoin price.

Bithumb said, "Through our internal control system, we immediately detected abnormal transactions and swiftly restricted trading for the related accounts."

It added, "As a result, the market price recovered to normal levels within 5 minutes, and the domino liquidation prevention system operated normally, so chain liquidations due to abnormal bitcoin prices also did not occur."

This dismissed concerns about "chain margin calls (liquidations)" that had been raised after bitcoin prices on Bithumb fell by more than 10 percent compared with other exchanges immediately after the incident.

Bithumb in particular stressed the incident was not a security breach.

Bithumb said, "This matter is unrelated to external hacking or security breaches, and we make clear there are no issues with system security or customer asset management," adding, "Customer assets are being managed safely as before, and trading and deposits and withdrawals are also operating normally."

On whether any damage occurred, it said, "It appears that no customer asset losses or damage occurred due to this matter," but added, "We will transparently share all follow-up measures and will take responsibility to the end so that not a single customer suffers harm."

Earlier, on the evening of Feb. 6, Bithumb mistakenly paid 2,000 BTC per person to about 695 event winners. The total amount of erroneously paid bitcoin was estimated at about 133 trillion won, dealing a major shock to the market.