Mt. Gox, founded in 2010, was one of the first and largest bitcoin exchanges. It handled around 70% of all bitcoin transactions at its peak. In 2014, it filed for bankruptcy after losing approximately 850,000 bitcoins, worth around $450 million at the time, due to suspected theft and security vulnerabilities. This event caused a major shock in the cryptocurrency market and highlighted the need for improved security and regulatory oversight in the industry.