Mt. Gox
A Tokyo exchange built on top of a Magic: The Gathering trading site briefly handled most of the world's Bitcoin. Then 850,000 coins quietly walked out the door.
Mt. Gox started life as a place to trade Magic: The Gathering cards. The acronym itself preserved the original purpose: Magic: The Gathering Online Exchange. By 2013, after a series of pivots and an acquisition by a French expat named Mark Karpelès, it was the venue through which roughly seventy percent of all Bitcoin trades on Earth flowed.
A leak that was not noticed
The leak ran for years. Coins drained out of the exchange's hot wallets through a combination of weak internal accounting, sloppy key management, and what investigators later concluded was steady external theft. The total losses eventually reached around 850,000 bitcoins, or roughly half a billion dollars at the time and many times that at later prices.
Mt. Gox itself appears to have been genuinely surprised when the cumulative shortfall became impossible to ignore in February 2014. The exchange suspended withdrawals, then suspended trading, then filed for bankruptcy protection in Tokyo.
The Karpelès trial and the long unwinding
Karpelès was eventually charged in Japan, convicted on a narrow charge of falsifying records, and acquitted of embezzlement. A separate US indictment later named two Russian nationals as the actual operators of the long-running theft, identified through laundering patterns on a related exchange called BTC-e.
What the chronicle remembers
Mt. Gox is the founding trauma of crypto custody. Every "not your keys, not your coins" t-shirt traces back, in some sense, to the months in 2014 when ordinary people learned that an exchange could simply lose the money and have nothing left to give back.