The S&P 600 is a stock market index tracking the stock performance of 600 companies listed on stock exchanges in the United States that are considered to have small market capitalizations. The S&P 600 is a subset of the S&P 1500. It is maintained by S&P Dow Jones Indices and its components are selected by a committee.
The index is a public-float-weighted/capitalization-weighted index. The index includes approximately 2.5% of the total market capitalization of U.S. public companies, with an aggregate market capitalization of more than $1.4 trillion as of December 31, 2025. The median market capitalization of the components of the index is $2.6 billion and components range in market capitalization from $357 million to $12.1 billion.
Products linked to the S&P 600 include index funds as well as derivatives, which are available for trading in many countries with the goal of replicating the performance of the index.Wikipedia