Robinhood stock has continued to stumble to new all-time lows following that lock-up expiration. On the bright side, ARK Invest's Cathie Wood added over 900,000 shares of Robinhood to the ARK Innovation ETF a day before the lockup period ended. As of this writing, the fund still holds 11.7 million shares of Robinhood as 1.57% of its portfolio.