History of S&P 500 in Timeline

The S&P 500 is a stock market index representing the performance of 500 of the largest publicly traded companies in the United States. It captures approximately 80% of the total U.S. market capitalization. With an aggregate market cap of over $49.8 trillion as of March 31, 2025, the S&P 500 is a widely followed indicator of the U.S. stock market's health and overall economic condition.

1906: Standard Statistics Bureau Founded

In 1906, the Standard Statistics Bureau was founded, later becoming the Standard Statistics Company.

1923: First Stock Market Index

In 1923, the Standard Statistics Company developed its first stock market index, consisting of the stocks of 233 U.S. companies, computed weekly.

1926: S&P 500 Inception

Since its inception in 1926, the index's compound annual growth rate—including dividends—has been approximately 9.8%.

1941: Formation of Standard & Poor's

In 1941, Poor's Publishing merged with Standard Statistics Company to form Standard & Poor's.

March 4, 1957: S&P 500 Expansion

On March 4, 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 Becomes Compiler

In 1962, Ultronic Systems became the compiler of the S&P indices, including the S&P 500 Stock Composite Index.

August 31, 1976: First Mutual Fund Tracking S&P 500

On August 31, 1976, The Vanguard Group offered the first mutual fund to retail investors that tracked the index.

April 21, 1982: CME Began Trading Futures

On April 21, 1982, the Chicago Mercantile Exchange (CME) began trading futures based on the index.

1982: Original SP Big Contract began Trading

The original SP big contract began trading in 1982.

July 1, 1983: CBOE Began Trading Options

On July 1, 1983, the Chicago Board Options Exchange began trading options based on the index.

1986: Index Update Frequency Increased

Beginning in 1986, the index value was updated every 15 seconds, with price updates disseminated by Reuters.

January 22, 1993: S&P Depositary Receipts ETF Trading Begins

On January 22, 1993, the Standard & Poor's Depositary Receipts exchange-traded fund issued by State Street Corporation began trading.

September 9, 1997: S&P E-mini Futures Contract Introduced

On September 9, 1997, CME Group introduced the S&P E-mini futures contract.

2005: Transition to Public Float-Adjusted Weighting

In 2005, the index transitioned to a public float-adjusted capitalization-weighting.

September 17, 2021: Final Trading Date for SP Big Contract

Friday, September 17, 2021, was the final trading date for the original SP big contract which began trading in 1982.

October 2021: NBER Study on Ratings Services

In October 2021, a study by the National Bureau of Economic Research suggested that companies' purchases of ratings services from S&P Global may improve their chance of entering the S&P 500.

March 31, 2025: S&P 500 Market Cap

On March 31, 2025, the S&P 500 had an aggregate market capitalization of more than $49.8 trillion.

2025: S&P 500 Record High and Correction

In 2025, the S&P 500 reached a record high of 6,280.46 on July 10th, followed by an intra-year correction to a low of 4,982.77 on April 8 before recovering.