The Russell 2000 is a stock market index comprised of the 2000 small smallest companies in the US markets. It is made up of the bottom two-thirds of the Russell 3000 index, a larger index of 3000 publicly traded companies that represent nearly 98 percent of the investable U.S. stock market. This index often serves as a benchmark for small-cap stocks in the United States, much like how the S&P 500 is a benchmark for large-cap stocks.

Investors use the Russell 2000 as a leading indicator of impending weakness in the overall markets and leverage this index to extract clues about market sentiment and trends.