The Standard and Poor’s 500, or simply the S&P 500, is a stock market index tracking the stock performance of 500 leading companies listed on stock exchanges in the United States. It is one of the most followed equity indices and includes approximately 80% of the total market capitalization of U.S. public companies, with an aggregate market cap of more than $49.8 trillion as of March 31, 2025.
The S&P 500 index is a public float weighted/capitalization-weighted index. The ten largest companies on the list of S&P 500 companies account for approximately 38% of the market capitalization of the index and the 50 largest components account for 60% of the index. The 10 largest components are, in order of highest to lowest weighting: Nvidia (8.1%), Microsoft (7.3%), Apple (5.8%), Amazon.com (3.9%), Alphabet (3.9%, including both class A & C shares), Meta Platforms (3.0%), Broadcom (2.7%), Berkshire Hathaway (1.6%), Tesla (1.6%), and JPMorgan Chase (1.5%). The components that have increased their dividends in 25 consecutive years are known as the S&P 500 Dividend Aristocrats. Companies in the S&P 500 derive a collective 72% of revenues from the United States and 28% from other countries.
History
- 1923 – Standard Statistics Company (founded in 1906 as the Standard Statistics Bureau) began rating mortgage bond and developed its first stock market index consisting of the stocks of 233 U.S. companies, computed weekly.
- 1926 – A 90-stock index which is computed daily is developed.
- 1941- Poor’s Publishing is merged with Standard Statistics Company to form Standard & Poor’s.
- March 1957 – The index was expanded to its current extent of 500 companies and was renamed the S&P 500 Stock Composite Index.
- 1962 – Ultronic Systems became the compiler of the S&P indices including the S&P 500 Stock Composite Index, the 425 Stock Industrial Index, the 50 Stock Utility Index, and the 25 Stock Rail Index.
- August 1976 – The Vanguard Group offered the first mutual fund to retail investors that tracked the index.
- April 1982 – The Chicago Mercantile Exchange began trading futures based on the index.
- July 1983 – Chicago Board Options Exchange began trading options based on the index.
- Early 1986 – The index value was updated every 15 seconds, or 1,559 times per trading day, with price updates disseminated by Reuters. Prior to this, it had been updated once every minute.
- January 1993 – The Standard & Poor’s Depositary Receipts exchange-traded fund issued by State Street Corporation began trading.
- September 1997 – CME Group introduced the S&P E-mini futures contract.
- 2005 – The index transitioned to a public float-adjusted capitalization-weighting.
Selection Criteria of Stocks
The components of the S&P 500 are selected by a committee. When considering the eligibility of a new addition, the committee assesses the company’s merit using the following primary criteria:
Market capitalization: Market capitalization must be greater than or equal to US$22.7 billion (effective on July 1, 2025). These market cap eligibility criteria are for addition to an index, not for continued membership. As a result, an index constituent that appears to violate criteria for addition to that index is not removed unless ongoing conditions warrant an index change.
Market liquidity and public float: Annual dollar value traded to float-adjusted market capitalization is greater than 0.75.
Volume: Minimum monthly trading volume of 250,000 shares in each of the six months leading up to the evaluation date.
Stock exchange: Must be publicly listed on the New York Stock Exchange (including NYSE Arca or NYSE American), Nasdaq (Nasdaq Global Select Market, Nasdaq Select Market or the Nasdaq Capital Market) or Cboe (Cboe BZX, Cboe BYX, Cboe EDGA or Cboe EDGX).
Domicile: The company must have its primary listing on a U.S. exchange.
Securities that are ineligible for inclusion in the index are limited partnerships, master limited partnerships and their investment trust units, OTC Bulletin Board issues, closed-end funds, exchange-traded funds, Exchange-traded notes, royalty trusts, tracking stocks, preferred stock, unit trusts, equity warrants, convertible bonds, investment trusts, American depositary receipts, and American depositary shares.
A stock may rise in value when it is added to the index since index funds must purchase that stock to continue tracking the index.
Historical Returns
Since its inception in 1926, the index’s compound annual growth rate including dividends has been approximately 9.8% (6% after inflation), with the standard deviation of the return, calculated on a monthly basis, over the same time period being 20.81%. While the index has declined in several years by over 30%, it has posted annual increases 70% of the time, with 5% of all trading days resulting in record highs. The S&P 500’s record high of 6,280.46 was set on July 10th, 2025.
Returns are generally quoted as price returns (excluding returns from dividends). However, they can also be quoted as total return, which includes returns from dividends and the reinvestment thereof, and “net total return”, which reflects the effects of dividend reinvestment after the deduction of withholding tax.
| Year | Change in Index | Total Annual Return, including Dividends |
| 1961 | 23.13% | – |
| 1962 | -11.81% | – |
| 1963 | 18.89% | – |
| 1964 | 12.97% | – |
| 1965 | 9.06% | – |
| 1966 | -13.09% | – |
| 1967 | 20.09% | – |
| 1968 | 7.66% | – |
| 1969 | -11.36% | – |
| 1970 | 0.10% | 4.01% |
| 1971 | 10.79% | 14.31% |
| 1972 | 15.63% | 18.98% |
| 1973 | −17.37% | −14.66% |
| 1974 | −29.72% | −26.47% |
| 1975 | 31.55% | 37.20% |
| 1976 | 19.15% | 23.84% |
| 1977 | −11.50% | −7.18% |
| 1978 | 1.06% | 6.56% |
| 1979 | 12.31% | 18.44% |
| 1980 | 25.77% | 32.50% |
| 1981 | −9.73% | −4.92% |
| 1982 | 14.76% | 21.55% |
| 1983 | 17.27% | 22.56% |
| 1984 | 1.40% | 6.27% |
| 1985 | 26.33% | 31.73% |
| 1986 | 14.62% | 18.67% |
| 1987 | 2.03% | 5.25% |
| 1988 | 12.40% | 16.61% |
| 1989 | 27.25% | 31.69% |
| 1990 | −6.56% | −3.10% |
| 1991 | 26.31% | 30.47% |
| 1992 | 4.46% | 7.62% |
| 1993 | 7.06% | 10.08% |
| 1994 | −1.54% | 1.32% |
| 1995 | 34.11% | 37.58% |
| 1996 | 20.26% | 22.96% |
| 1997 | 31.01% | 33.36% |
| 1998 | 26.67% | 28.58% |
| 1999 | 19.53% | 21.04% |
| 2000 | −10.14% | −9.10% |
| 2001 | −13.04% | −11.89% |
| 2002 | −23.37% | −22.10% |
| 2003 | 26.38% | 28.68% |
| 2004 | 8.99% | 10.88% |
| 2005 | 3.00% | 4.91% |
| 2006 | 13.62% | 15.79% |
| 2007 | 3.53% | 5.49% |
| 2008 | −38.49% | −37.00% |
| 2009 | 23.45% | 26.46% |
| 2010 | 12.78% | 15.06% |
| 2011 | 0.00% | 2.11% |
| 2012 | 13.41% | 16.00% |
| 2013 | 29.60% | 32.39% |
| 2014 | 11.39% | 13.69% |
| 2015 | −0.73% | 1.38% |
| 2016 | 9.54% | 11.96% |
| 2017 | 19.42% | 21.83% |
| 2018 | −6.24% | −4.38% |
| 2019 | 28.88% | 31.49% |
| 2020 | 16.26% | 18.40% |
| 2021 | 26.89% | 28.71% |
| 2022 | −19.44% | −18.11% |
| 2023 | 24.23% | 26.29% |
| 2024 | 23.31% | 25.02% |
| High | 34.11% | 37.58% |
| Low | −38.49% | −37.00% |
| Median | 12.40% | 15.79% |
Other S&P Index Family
Float-Adjusted Market Capitalization (FMC) Weighted Indices
S&P Total Market Index: The index measures the performance of the broad U.S. market and includes all eligible U.S. common equities.
S&P 500: The index measures the performance of the large-cap segment of the U.S. market. Considered to be a proxy of the U.S. equity market, the index is composed of 500 constituent companies.
S&P MidCap 400: The index measures the performance of the mid-cap segment of the U.S. market. The index is composed of 400 constituent companies.
S&P SmallCap 600: The index measures the performance of the small-cap segment of the U.S. market. The index is composed of 600 constituent companies.
S&P Composite Indices: The indices include the S&P Composite 1500, S&P 900, and S&P 1000. The S&P Composite 1500 is a combination of the S&P 500, S&P MidCap 400, and S&P SmallCap 600 and measures the performance of all three market size segments. The S&P 900 is a combination of the S&P 500 and S&P MidCap 400 and measures the performance of the mid- and large-cap market size segments. The S&P 1000 is a combination of the S&P MidCap 400 and S&P SmallCap 600 and measures the performance of the mid- and small-cap market size segments.
S&P Completion Index: The index is a sub-index of the S&P Total Market Index and measures the performance of all constituents in the S&P Total Market Index that are not also constituents of the S&P 500. The Index is constituted at the company level, not at the share line level. If one company listing is in the S&P 500, all other company listings are excluded from the S&P Completion Index.
S&P 500 Top 10 Index: The index measures the performance of 10 of the largest, by FMC, companies in the S&P 500.
S&P 500 Top 20 Index: The index measures the performance of 20 of the largest, by FMC, companies in the S&P 500.
S&P 500 Top 50: The index measures the performance of 50 of the largest, by FMC, companies in the S&P 500.
S&P 100: The index measures the performance of 100 companies selected from the S&P 500. Generally, the largest companies in the S&P 500 that have listed options are selected for index inclusion. Sector balance is also considered in the selection of companies for the S&P 100.
