As is common with all centralized exchanges, Poloniex keeps control of all private keys to the online wallets holding the users’ cryptocurrencies. However, most of the funds are in secure offline “cold storage.” The exchange offers browser recognition tools and two-factor authentication for account holders. In 2014, the exchange was hacked and almost 12% of all customer Bitcoin deposits were stolen. The exchange immediately announced that all the funds would be reimbursed. Given that Poloniex See full review