Coinbase says it is still investigating the matter. "If we find evidence of any employee or contractor violating our policies — directly or indirectly — I will not hesitate to terminate the employee immediately and take appropriate legal action," CEO Brian Armstrong wrote in a blog post. A Coinbase spokesperson said the company doesn't have new information to share at the moment. OKEx, another major cryptocurrency exchange, declined to share the trading rules that govern its employees in response to a Yahoo Finance inquiry, saying that such rules are, "strictly confidential and for internal use only." For now, without formal government regulations, the companies must self-police. And that's one element of the crypto world that turns off potential newcomers. Krystal Hu is a reporter at Yahoo Finance. Follow her on Twitter Read more: Bitcoin miner: 'I haven't paid for heat in three years' How Chinese bitcoin buyers are getting around the government ban This farming county in Washington is a bitcoin mining hub