https://www.recode.net/2018/2/26/17053194/circle-poloniex-acquisition-400-million

Circle, which runs a cryptocurrency platform that allows larger clients to trade bitcoin on the market, has bought one of the underlying exchanges, Poloniex, in a deal that values Poloniex at about $400 million.

The ballpark deal price, confirmed by a person with knowledge of the terms, is one of the larger transactions in the burgeoning cryptocurrency industry, though Circle itself remains private (and could go up or down in value). Poloniex is the 18th largest cryptocurrency exchange by trade volume, according to Coin Market Cap.