Mt. Gox Collapse

On February 24, 2014, Mt. Gox — at one point handling more than 70% of global Bitcoin volume — suspended trading and filed for bankruptcy protection in Japan. Roughly 850,000 BTC belonging to customers were missing. Valued at the time of bankruptcy, the loss was around $450M; at later BTC prices it would represent tens of billions.

What happened

Mt. Gox suffered persistent theft from its hot wallets between 2011 and 2014, with internal record-keeping that failed to detect the divergence between recorded balances and on-chain reality. The DOJ later charged Alexander Vinnik, operator of the BTC-e exchange, with laundering a significant portion of the stolen coins. Earlier breaches in 2011 — including the well-known "$0.01 BTC" price-feed manipulation — had already drained substantial customer funds.

Mt. Gox publicly attributed the failure to transaction malleability, which would have let users alter transaction hashes to make withdrawals appear failed. Subsequent analysis (and the eventual recovery of ~200,000 BTC in a forgotten cold wallet) established that the malleability narrative was largely a cover for years of undetected theft.

Aftermath

• The Japanese bankruptcy trustee recovered roughly 200,000 BTC from a previously overlooked wallet.
• Rehabilitation distributions to creditors began in 2024, more than ten years after the collapse.
• The case shaped early thinking on exchange custody, proof-of-reserves and audit practices — though as later events (FTX, QuadrigaCX) demonstrated, those lessons took another decade to take hold.

Why it matters

Mt. Gox is the founding case study for the rule that "not your keys, not your coins". It established the pattern of centralized custodians failing through a combination of inadequate controls, fraud and external theft — a pattern that has recurred at scale ever since.