Best index funds to invest in for May 2023 Fidelity ZERO Large Cap Index. Vanguard S&P 500 ETF. SPDR S&P 500 ETF Trust. iShares Core S&P 500 ETF. Schwab S&P 500 Index Fund. Shelton NASDAQ-100 Index Direct. Invesco QQQ Trust ETF. Vanguard Russell 2000 ETF. More items... May 15, 2023