SEOUL, Feb. 7 -- South Korean cryptocurrency exchange Bithumb has confirmed it accidentally distributed more than $40 billion worth of bitcoins to customers as part of a promotional reward, triggering a brief selloff on the platform.

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The incident occurred on Friday, when the exchange intended to award users small cash rewards of 2,000 Korean won (about $1.37) each. Instead, 695 customers received at least 2,000 bitcoins each, media reports said. Bithumb quickly restricted trading and withdrawals within 35 minutes and said it has recovered 99.7% of the mistakenly distributed 620,000 bitcoins, valued at roughly $44 billion at current prices.

"We would like to make it cle...