Key Management Failure at Scale
Mt. Gox handled over 70% of global Bitcoin trading by early 2014. Between 2011 and 2014, approximately 850,000 BTC (including 750,000 belonging to customers) were systematically stolen after the exchange's hot wallet private key was extracted from a wallet.dat file in 2011. Poorly secured centralised key storage, absent cold wallet segregation, and no anomaly detection on transaction flows allowed the theft to continue undetected for years.
Mt. Gox filed for bankruptcy in February 2014. After a decade of legal proceedings, the estate holds approximately 34,500 BTC for creditor distribution.
Lesson: Centralised private key storage without access controls, independent auditing, or cold wallet segregation is not a risk: it is a certainty of eventual loss.