KoinlyticsMt. Gox was Bitcoin's first dominant exchange. At its 2013 peak it handled 70%+ of global BTC trading. In February 2014 it declared bankruptcy, admitting 850,000 BTC (7% of all BTC in existence) were missing. It remains the largest crypto loss ever.
What actually happened
Not a single hack — years of slow drain. Investigations later suggested most of the missing BTC was stolen incrementally starting in 2011 by exploiting a wallet-management bug. Mt. Gox's founder Mark Karpelès denies criminal knowledge; he was later convicted only of falsifying records.
The transaction malleability distraction
Mt. Gox blamed "transaction malleability" in its 2014 announcement. This was largely a cover: malleability was a real Bitcoin quirk, but not the mechanism by which coins were stolen. The narrative delayed regulator understanding.
The market impact
Bitcoin fell from ~$1,150 to under $200 over the following months. The industry was set back years. Trust in exchanges collapsed and never fully returned to pre-Mt. Gox levels.
The 2024 payout
10 years later, the Mt. Gox trustee began distributing recovered BTC (~140,000 of the missing 850,000) to creditors. Payouts started in July 2024. Creditors who filed for BTC receive BTC (now worth 60x their filing-date value); those who took cash claims received far less.
What the industry learned
- Never leave meaningful holdings on exchanges long-term.
- Proof-of-reserves became a standard demand.
- Cold storage best practices became mainstream.
- Compliance and audit expectations tightened.
The parallel warning
Mt. Gox took 3 years of quiet insolvency before collapsing. FTX did the same in 2022. When large exchanges refuse to publish real proof of reserves, assume Mt. Gox-style history is possible.