According to @StockMKTNewz, Robinhood (HOOD) will officially be added to the S&P 500 when the U.S. stock market opens tomorrow, setting up an index-event trading session. Source: @StockMKTNewz on X, Sep 21, 2025. Index-tracking funds and ETFs that replicate the S&P 500 are required by mandate to add new constituents at the effective time, creating mechanically forced buying and potential volume spikes in HOOD around the open. Source: S&P Dow Jones Indices, S&P U.S. Indices Methodology. S&P 500 additions are typically implemented at the opening auction on the effective date, which can produce notable opening imbalance orders and short-term price impact for the added stock. Source: S&P Dow Jones Indices, S&P U.S. Indices Methodology; NYSE/Nasdaq auction procedures. Because Robinhood’s business includes crypto trading in major assets such as BTC and ETH, HOOD’s fundamentals are partially sensitive to retail crypto trading activity, linking stock performance more closely to crypto market sentiment than many S&P 500 constituents. Source: Robinhood Markets Investor Relations and Robinhood Crypto product disclosures. Traders should monitor opening-cross imbalances, ETF basket activity for S&P 500 trackers, and cross-asset volatility in BTC and ETH as inputs for HOOD’s liquidity and intraday risk following the inclusion. Source: S&P Dow Jones Indices, S&P U.S. Indices Methodology; SPDR S&P 500 ETF Trust, iShares Core S&P 500 ETF, Vanguard S&P 500 ETF fund mandates.