The Russell 2500 Index measures the performance of the 2,500 smallest companies in the Russell 3000 Index, with a weighted average market capitalization of approximately $4.3 billion, median capitalization of $1.2 billion and market capitalization of the largest company of $18.7 billion.
The index was launched on June 1, 1990 by Russell Investments and is maintained by FTSE Russell, a subsidiary of the London Stock Exchange Group. Its ticker symbol is ^R25I.Wikipedia