Mark Karpelès: The Man Who Lost 850,000 Bitcoin

Ran Mt. Gox, the world's largest Bitcoin exchange, straight into the ground.

Mark Karpelès was a French developer living in Tokyo who somehow ended up running the world's largest Bitcoin exchange. He'd acquired Mt. Gox in 2011 from its creator Jed McCaleb (who would later co-found Stellar and Ripple). At its peak, Mt. Gox handled over 70% of all Bitcoin transactions on Earth.

The exchange was held together with duct tape and prayers. Karpelès was a one-man engineering team running a platform that handled hundreds of millions of dollars. There was no proper accounting, no security audit, and the codebase was a disaster. While BTC was disappearing from the exchange's wallets over the course of years, Karpelès appeared to be more focused on building a Bitcoin café in Tokyo.

In February 2014, Mt. Gox went offline. Then it filed for bankruptcy. Then Karpelès admitted that 850,000 Bitcoin - 6% of all BTC in existence - were gone. Some had been stolen through a long-running hack. Some were lost through incompetence. The exact breakdown remains debated.

Karpelès was arrested in Japan in 2015 on charges of embezzlement and data manipulation. After spending nearly a year in Japanese detention (notorious for its 99% conviction rate), he was convicted of data manipulation but acquitted of embezzlement in 2019. He received a suspended sentence.

The Mt. Gox creditor repayment saga dragged on for a full decade. Those 127,000 creditors who lost their BTC at $460 each finally started receiving partial repayments in 2024 - when each Bitcoin was worth over $60,000. Some of the worst luck in crypto turned into the longest involuntary hold in history.