According to Michael Saylor on Twitter, Coinbase's stock ($COIN) has been officially added to the S&P 500 Index, marking a significant milestone for both Coinbase and the broader Bitcoin market (source: @saylor, May 12, 2025). This inclusion increases institutional exposure to crypto-related equities, potentially boosting $COIN trading volumes and impacting Bitcoin-linked ETF flows. Traders should monitor $COIN price action as S&P 500 index funds and ETFs adjust their portfolios, which could drive additional volatility and liquidity in both crypto and traditional equity markets.