S&P 500

Tracks 500 large-cap US companies across all sectors. The primary benchmark for US equity market performance, representing roughly 80% of US market capitalization.

The S&P 500 is the de facto benchmark for US equity performance and the most widely tracked index on earth. Over long periods it has returned roughly 10% annually including dividends — a fact that has made passive index investing the dominant strategy in retail and institutional portfolios alike.

Membership requires a committee decision (not purely mechanical): companies must have a minimum free-float market cap of approximately $18B, demonstrate four consecutive quarters of GAAP profitability, and meet liquidity thresholds. The market-cap weighting means a handful of mega-cap technology companies — Apple, NVIDIA, Microsoft — now dominate returns, creating meaningful concentration risk that was absent in earlier decades.