On April 22, 2017, Yapizon suffered an attack where hackers compromised four hot wallets and stole 3,816 BTC (~$5M), representing 37% of user funds. South Korean authorities later alleged the breach was perpetrated by North Korea. Yapizon replaced lost balances with Fei tokens representing IOUs.

Yapizon, a South Korean Bitcoin exchange, announced last week it lost 3831 Bitcoin (over $5.5 million) after an unknown hacker breached its system and stole funds from its server.