Mt. Gox pre-collapse on-chain warning sign

On February 5, 2014, deposit-era Mt. Gox-controlled wallets shuffled coins in volumes the chain had never seen — 143.6 million BTC·days destroyed in a single day, more than fifty standard deviations above the trailing thirty-day baseline. There was no public news that day.

Three weeks later, on February 24, Mt. Gox suspended all withdrawals. On February 28 they filed for bankruptcy. The 850,000 BTC "lost to hackers" turned out to have been mostly an internal accounting and custody catastrophe that had been brewing for years. Subsequent on-chain forensics traced the February 5 movements to consolidation of cold-storage wallets that the exchange was scrambling to reconcile against customer balances it could not deliver.

This is the cleanest historical example of CDD anticipating a market-moving event. The signal was visible on chain weeks before anyone outside Mt. Gox knew there was a problem.