Jed McCaleb launches Mt. Gox on July 18, 2010, which would become the world's largest Bitcoin exchange, handling over 70% of all Bitcoin transactions at its peak. The name came from "Magic: The Gathering Online eXchange," a domain McCaleb had originally registered for trading game cards. McCaleb later sold the site to Mark Karpeles in March 2011. Mt. Gox would ultimately collapse in February 2014 after losing approximately 850,000 BTC, making it the most infamous exchange failure in Bitcoin history.
Wikipedia: Mt. Gox