S&P 500

thumb|Though there is large variability in month-to-month changes in the S&P 500 (gray lines), a seasonal pattern emerges when the monthly change values are averaged (bold line).

[[File:S&P 500 Max Min Log Chart to Jan 2026 with Trend and other plots.svg|thumb|S&P 500 Max Min Log Chart to Jan 2026 with Trend, with plots less Inflation and other plots for comparison

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S&P 500 (Standard and Poor's 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 commonly 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 $61.1 trillion as of December 31, 2025.

The S&P 500 index is a public float weighted/capitalization-weighted index. The ten largest companies on the S&P 500 index account for approximately 38% of the market capitalization of the index and the 50 largest components account for 60% of the index. As of January 2026, the 10 largest components are, in order of highest to lowest weighting: Nvidia (7.17%), Alphabet (6.39%, including both class A & C shares), Apple (5.86%), Microsoft (5.33%), Amazon (3.98%), Broadcom (2.51%), Meta Platforms (2.49%), Tesla (2.31%), Berkshire Hathaway (1.68%), and Lilly (Eli) (1.55%). Companies in the S&P 500 derive a collective 72% of revenues from the United States and 28% from other countries.

The index is one of the factors in the computation of the Conference Board Leading Economic Index, which is used to forecast the direction of the economy. The index is associated with many ticker symbols, including ^GSPC,. INX, and SPX, depending on market or website. The S&P 500 is maintained by S&P Dow Jones Indices, a joint venture majority-owned by S&P Global, and its components are selected by a committee.

Direxion offers leveraged ETFs which attempt to produce 3x the daily return of either investing in () or shorting () the S&P 500. ProShares offers 2x daily return () and 3x daily return ().

Derivatives

In the derivatives market, the Chicago Mercantile Exchange (CME) offers futures contracts that track the index and trade on the exchange floor in an open outcry auction, or on CME's Globex platform, and are the exchange's most popular product. The Chicago Board Options Exchange (CBOE) offers options on the S&P 500 as well as on S&P 500 ETFs, inverse ETFs, and leveraged ETFs.

History

In 1860, Henry Varnum Poor formed Poor's Publishing, which published an investor's guide to the railroad industry. In 1923, Standard Statistics Company (founded in 1906 as the Standard Statistics Bureau) began rating mortgage bonds Three years later, it developed a 90-stock index, computed daily.

On Monday, March 4, 1957, the index was expanded to its current extent of 500 companies and was renamed the S&P 500 Stock Composite Index. On August 31, 1976, The Vanguard Group offered the first mutual fund to retail investors that tracked the index.

On January 22, 1993, the Standard & Poor's Depositary Receipts exchange-traded fund issued by State Street Corporation began trading. Friday, September 17, 2021, was the final trading date for the original SP big contract which began trading in 1982.

Selection criteria

Like other indices managed by S&P Dow Jones Indices, but unlike indices such as the Russell 1000 Index which are strictly rule-based, 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: 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.

VolumeMinimum monthly trading volume of 250,000 shares in each of the six months leading up to the evaluation date
Stock exchangeMust 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).
DomicileThe 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 study published by the National Bureau of Economic Research in October 2021 alleged that companies' purchases of ratings services from S&P Global appear to improve their chance of entering the S&P 500, even if they are not the best fit per the rules.

Performance

thumb|500px|S&P 500 Buybacks and Dividends (quarterly) <br /> [[Stock buyback <br /> Dividends]]

500px|right|S&P 500 annual 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.

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.

Derivatives

History

Selection criteria

Performance

See also

References