Coinbase Inc. is losing its president and chief operating officer, former TD Ameritrade Holdings Corp. executive Asiff Hirji, the latest in a series of departures by senior executives at the San Francisco-based cryptocurrency exchange.

Hirji joined in December 2017, when the price of Bitcoin was peaking and the firm was seeing some of the largest trading demand in its history. Hirji played a large role in steering the startup through the roller coaster ride of cryptocurrency price swings that came late in 2017 and thereafter. While he was in the role, the firm started making a bigger push into international markets and products for institutional firms. Emilie Choi, vice president of business, data and international, was named chief operating officer, according to a company statement.

“His experience and mentorship helped guide Coinbase through an important chapter in its history,” Brian Armstrong, Coinbase co-founder and chief executive officer, said in the statement. “He joined at a critical time when both the company and crypto space were going through rapid growth, bringing his extensive experience to bear when it was most necessary.”

Hirji’s exit comes amid a slew of others at the closely held company. Since late 2018, the firm has lost Chief Technology Officer Balaji Srinivasan, as well as leaders in its institutional offering including Dan Romero, Adam White and Christine Sandler. Executive turnover has caused some concern among analysts over the direction of the firm, but Coinbase argues that its new business lines are continuing to grow rapidly, with its custody product now holding more than US$1 billion worth of crypto, and its platform accounting for half of trading volume for regulated exchanges in the U.S., up from 17 per cent two years ago.

Choi was one of Hirji’s first hires and she has been working closely with Armstrong on looking at potential partnerships, acquisitions, and was instrumental in the firm’s most recent funding round, according to a person familiar with the situation who agreed to speak anonymously due to the private nature of the information. Hirji’s last day was Thursday.

She started her Silicon Valley career at Yahoo! Inc. and worked on the original Alibaba investment and Flickr acquisition, Coinbase said. Choi also worked at LinkedIn Corp., where she drove the company’s entry into China, according to the crypto exchange.