Why invest in crypto index funds? Probably the best known index fund for stocks is the S&P500. This tracks the market value of 500 large US stocks. By investing in the S&P500 (via Vanguard, Schwab, Blackrock or State Street), one can get exposure to the performance of the US stock market. Crucially, investing in index funds provides the benefit of wide diversification (roughly across 500 stocks) without high fees (typically less than 0.25%) and without needing to proactively manage one's investments.