History of S&P 500 in Timeline

The S&P 500 is a stock market index that tracks the performance of 500 of the largest publicly traded companies in the United States. Representing approximately 80% of the total U.S. market capitalization, it serves as a benchmark for the overall health and performance of the U.S. equity market. The S&P 500's aggregate market capitalization was over $57.401 trillion as of August 29, 2025, making it a widely followed indicator of the U.S. economy.

1860: Poor's Publishing Formed

In 1860, Henry Varnum Poor created Poor's Publishing, which was created to publish an investor's guide to the railroad industry.

1906: Standard Statistics Bureau Founded

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

1923: Standard Statistics Company's First Stock Market Index

In 1923, the Standard Statistics Company started rating mortgage bonds and created its first stock market index, which consisted of stocks from 233 U.S. companies and was computed weekly.

1926: S&P 500 Inception

Since its inception in 1926, the S&P 500 index has demonstrated a compound annual growth rate of approximately 9.8% including dividends (6% after inflation).

1941: Formation of Standard & Poor's

In 1941, Poor's Publishing merged with Standard Statistics Company, leading to the establishment of Standard & Poor's.

March 4, 1957: S&P 500 Expansion

On March 4, 1957, the index expanded to 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, the 425 Stock Industrial Index, the 50 Stock Utility Index, and the 25 Stock Rail Index.

August 31, 1976: First Mutual Fund Tracking the Index

On August 31, 1976, The Vanguard Group introduced the first mutual fund to retail investors that tracked the S&P 500 index.

April 21, 1982: Futures Trading on the Index

On April 21, 1982, the Chicago Mercantile Exchange started trading futures based on the S&P 500 index.

1982: Original SP big contract began trading

In 1982, original SP big contract began trading.

July 1, 1983: Options Trading on the Index

On July 1, 1983, the Chicago Board Options Exchange began trading options based on the S&P 500 index.

1986: Index Value Update Frequency Increase

Beginning in 1986, the S&P 500 index value was updated every 15 seconds, disseminated by Reuters, a significant increase from the previous update frequency of once per minute.

January 22, 1993: Standard & Poor's Depositary Receipts exchange-traded fund

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

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

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

2005: Transition to Public Float-Adjusted Capitalization-Weighting

In 2005, the S&P 500 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: Study on S&P Global Ratings Services

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

August 29, 2025: S&P 500 Market Cap

On August 29, 2025, the S&P 500 had an aggregate market capitalization of more than $57.401 trillion.

September 2025: S&P 500 Top 10 Companies

In September 2025, the 10 largest components of the S&P 500 were: Nvidia, Microsoft, Apple, Alphabet (Class A & C shares), Amazon, Meta Platforms, Broadcom, Tesla, Berkshire Hathaway, and JPMorgan Chase.