Mt. Gox was a bitcoin exchange based in Shibuya, Tokyo, Japan. Launched in 2010, it was handling over 70% of all bitcoin (BTC) transactions worldwide by early 2014, when it abruptly ceased operations amid revelations of its involvement in the loss/theft of hundreds of thousands of bitcoins, then worth hundreds of millions in US dollars. Although 200,000 bitcoins have since been "found", the reasons for the disappearance—theft, fraud, mismanagement, or a combination of these—were initially unclear.

The founder of Canada's largest cryptocurrency exchange, QuadrigaCX, died unexpectedly in 2019. He was the only person with access to the exchange's cold wallets, resulting in approximately $190 million in customer funds being inaccessible.

BitPay, a company that provides Bitcoin payment solutions for merchants, fell victim to a phishing attack in 2015. The attacker, posing as a partner company, tricked BitPay into sending 5000 Bitcoins, worth approximately $1.8 million at the time.