S&P 500
The S&P 500 is a stock index tracking about 500 of the largest US public companies, widely used as the benchmark for the US stock market.
The S&P 500 is an index of roughly 500 of the largest companies listed on US exchanges, weighted by market capitalization so bigger companies count for more. Maintained by S&P Dow Jones Indices, it covers around 80% of the total value of the US stock market and is the single most-cited gauge of "how the market is doing."
Membership is not purely mechanical — a committee selects constituents based on size, liquidity, profitability, and US domicile, so the count hovers near 500 (it can differ slightly because some companies have multiple share classes). Being added to or dropped from the index is closely watched, because the many funds that track it must buy or sell the stock accordingly.
stocks-llm covers the full S&P 500 alongside the NASDAQ-100, Dow, and Russell 1000/2000. The live list below shows the largest S&P 500 members in the catalog by market cap, as delayed data with its as-of date.
Largest S&P 500 companies in the catalog
| Company | Market cap | |
|---|---|---|
| 1 | Nvidia (NVDA) | $5.01T |
| 2 | Apple Inc. (AAPL) | $4.76T |
| 3 | Alphabet Inc. (Class C) (GOOG) | $4.30T |
| 4 | Alphabet Inc. (Class A) (GOOGL) | $4.30T |
| 5 | Microsoft (MSFT) | $2.91T |
Live from the catalog, as of 2026-07-21 — delayed data from SEC EDGAR + Finnhub.
Largest companies by market cap →
See more terms in the stocks-llm glossary.
Informational only — NOT financial advice. This is an educational definition, not a recommendation to buy or sell anything. Metrics on stocks-llm are delayed data and may be missing or stale. Always verify information independently and consult a qualified financial professional before making any investment decision.