S&P 500

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 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 $57.401 trillion as of August 29, 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. As of September 2025, the 10 largest components are, in order of highest to lowest weighting: Nvidia (7.2%), Microsoft (6.3%), Apple (5.9%), Alphabet (5.0%, including both class A & C shares), Amazon (4.1%), Meta Platforms (3.2%), Broadcom (2.8%), Tesla (2.3%), Berkshire Hathaway (1.8%), and JPMorgan Chase (1.4%). 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.

The index is one of the factors in computation of the Conference Board Leading Economic Index, 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.

Index funds, including mutual funds and exchange-traded funds (ETFs), can replicate, before fees and expenses, the performance of the index by holding the same stocks as the index in the same proportions. ETFs that replicate the performance of the index are issued by The Vanguard Group (NYSE Arca: VOO), iShares (NYSE Arca: IVV), and State Street Corporation (SPDR S&P 500 ETF Trust, NYSE Arca: SPY and NYSE Arca: SPLG). The most liquid based on average daily volume is (NYSE Arca: SPY), although SPY has a higher annual expense ratio of 0.09% compared to 0.03% for VOO and IVV, and 0.02% for SPLG. Mutual funds that track the index are offered by Fidelity Investments, T. Rowe Price, and Charles Schwab Corporation.

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

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.

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 and developed its first stock market index consisting of the stocks of 233 U.S. companies, computed weekly. Three years later, it developed a 90-stock index, computed daily. In 1941, Poor's Publishing merged with Standard Statistics Company to form Standard & Poor's.

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. In 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. On August 31, 1976, The Vanguard Group offered the first mutual fund to retail investors that tracked the index. On April 21, 1982, the Chicago Mercantile Exchange began trading futures based on the index. On July 1, 1983, Chicago Board Options Exchange began trading options based on the index. Beginning in 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.