Bitfinex is the largest and most advanced cryptocurrencies exchange, owned and operated by iFinex Inc. which is headquartered in Hong Kong and registered in the British Virgin Islands.
In 2015 the exchange's customers were hacked, losing about $400,000, and in 2016 about $73 million more was stolen from its customers' accounts. The exchange's access to U.S. dollar payments and withdrawals has been curtailed.
In October 2018, Bitfinex again had serious difficulties with its banking relationships. Its management stated "Bitfinex is not insolvent on October 7."
Research suggests that price manipulation of bitcoin on Bitfinex accounted for about half of the price increase for bitcoin in late 2017.