It includes 1,000 of the smallest securities in the Russell 2000 Index based on a combination of their market cap and current index membership and it also includes up to the next 1,000 stocks.
As of 31 December 2016[update], the weighted average market capitalization for a company in the index was $535 million; the median market cap was $228 million.
The market cap of the largest company in the index was $3.6 billion.
The index, which was launched on June 1, 2005, is maintained by FTSE Russell, a subsidiary of the London Stock Exchange Group.
[1] The Russell Microcap Index is tracked by the iShares Micro-Cap ETF (NYSE Arca: IWC).