Robinhood Markets, Inc. (HOOD) shares soared 15.8% in the last trading session to close at $117.28. The move was backed by solid volume with far more shares changing hands than in a normal session. This compares to the stock's 11.7% loss over the past four weeks.On Sept. 5, the S&P Dow Jones Indices announced that Robinhood would join the S&P 500 as part of its quarterly rebalance, effective Sept. 22, replacing Caesars Entertainment. The move marks a major milestone for both Robinhood and the broader U.S. f ...