The Russell 2000 Index is a small-cap stock market index of the bottom 2,000 stocks in the Russell 3000 Index. The index is maintained by FTSE Russell, a subsidiary of the London Stock Exchange Group.
The Russell 2000 is by far the most common benchmark for mutual funds that identify themselves as "small-cap",
while the S&P 500 index is used primarily for large capitalization stocks. It is the most widely quoted measure of the overall performance of the small-cap to mid-cap company shares. The index represents approximately 8% of the total market capitalization of the Russell 3000 Index. As of 30 September 2018, the weighted average market capitalization for a company in the index is around $2.44 billion; the median market cap is $943 million. The market cap of the largest company in the index is $8.51 billion. It first traded above the 1,000 level on May 20, 2013.
Similar small-cap indices include the S&P 600 from Standard & Poor's,
which is less commonly used, along with those from other financial information providers.