Cryptocurrency exchange Coinbase, which is preparing to trade publicly in the next few months, is being valued at $77 billion, based on trading of the company's privately held shares on a secondary market. Those shares in the largest crypto exchange in the U.S. are changing hands on the Nasdaq Private Market at $303 a piece, according to two people with knowledge of the auction. That implies a total company value of about $77 billion - greater than Intercontinental Exchange Inc., the owner of the New York Stock Exchange. "The third weekly transaction closed on Friday and the clearing price was $303 a share," said a source. "The first week it was 200 bucks a share, the second week it was $301 a share, and the third week it was $303 a share. So you can kind of see price discovery happening." Coinbase declined to comment.