Cathie Wood’s Ark Investment Management announced in an e-mail that it purchased 78,982 shares of cryptocurrency exchange Coinbase (COIN), its first investment in the cryptocurrency exchange in a month.The purchase would have cost around $3 million at Friday’s closing price of $40.24. The stock has been in a slump in recent months, falling nearly 60% from a high of $98 in early August. The purchase brings the ARK Innovation ETF’s (ARKK) COIN holdings to 5.7 million. This is a small purchase that increases the ETF’s exposure by 1.4%. It suggests that the investment firm is still bullish on the crypto sector, but is taking a cautious approach while the dust settles on a rocky period.