There are many allegations that the Bitfinex exchange has been hacked. The attacker published a list of user emails to prove that they hacked Bitfinex. The Tether CEO, who is also the CTO of Bitfinex (2 companies run by the same group of people) stated that this appears to be fake, we still don't know the truth:
Paolo Ardoino: The database hack at Bitfinex appears to be unfounded. The data the hacker shared had only a few matches to Bitfinex users, and the company does not store passwords in plain text. Bitfinex suspects that this data comes from previous cryptocurrency hacks, as reuse of login information is common. There were no signs of any compromise detected in their systems, and they confirmed that all funds are safe. The situation is still being closely monitored.
