The Largest Theft $BTC In the early 2010s, Mt. Gox was a massive Bitcoin exchange, handling up to 70% of all transactions. In 2014, the exchange announced the loss of 850,000 BTC, which at that time amounted to about 450 million dollars, due to a hacking attack. This incident dealt a huge blow to the reputation of $BTC and the entire cryptocurrency market, causing a massive sell-off and price drop.