Russell 1000

The Russell 1000 is a US stock index that tracks roughly the 1,000 largest publicly traded American companies by market capitalization, maintained by FTSE Russell. It is widely used as the benchmark for large-cap mutual funds and ETFs.

Membership is determined mechanically during Russell's reconstitution, now held twice a year in June and December, ranking nearly the entire US stock market by size and drawing a line at the top 1,000 companies, with no committee discretion involved in who qualifies. This makes the Russell 1000 a purely size based index, in contrast to the S&P 500, where an index committee applies additional judgment around profitability and other criteria beyond just size.

The Russell 1000 overlaps heavily with the S&P 500 in practice, since both track large American companies, but the two indexes are not identical, and their differing construction rules occasionally lead one to include a company the other excludes.