According to its latest trading filing, ARK Innovation ETF (ARKK) bought 29,353 shares of Coinbase Global Inc. stock, worth about $5.2 million at Thursday's closing price. The ARKK Fund also bought 143,855 shares of Robinhood stock worth $5.18 million. Coinbase shares closed down 7.43% to $177.49. According to Google Finance, the cryptocurrency exchange's share price has fallen 31% so far this year.