Mt. Gox collapses

Mt. Gox, based in Tokyo and run by Mark Karpeles, once handled the majority of all bitcoin trading. In early February 2014 it stopped customer withdrawals, blaming a flaw known as transaction malleability. On February 24 its website went offline, and a leaked internal document said around 744,000 customer bitcoins were missing.

On February 28, 2014 Mt. Gox filed for bankruptcy protection in Tokyo, saying about 850,000 bitcoins in total were gone, 750,000 of them belonging to customers. It later found about 200,000 in an old wallet. Investigators eventually tied much of the loss to a theft that had been draining the exchange for years.

The collapse damaged trust in bitcoin for a long time and helped push the price into a long slide through 2014 and 2015. Creditors waited roughly a decade: the trustee began repaying customers in bitcoin and bitcoin cash in July 2024.

The lasting lesson is the one many guides still repeat: coins held on an exchange are only as safe as the exchange. See our wallet guide for the difference between custodial and self custody wallets.