NoSQL Meets Bitcoin and Brings Down Two Exchanges: The Story of Flexcoin and Poloniex. Flexcoin was a Bitcoin exchange that shut down on March 3rd, 2014, when someone allegedly hacked in and made off with 896 BTC in the hot wallet.
Because the half-million dollar heist from the hot wallet was too large for the company to bear, it folded. I'll resist the urge to ask why they did not have deposit insurance for their hot wallet, because the technical story of what happened is even more colorful and fascinating. Bitcoin Commodity Exchange - CEX.IO. ($454.99) Bitstamp - buy and sell bitcoins. Buttercoin.