So investiert der iShares Russell 1000 ETF: The investment seeks to track the investment results of the Russell 1000® Index, which measures the performance of large- and mid- capitalization sectors of the U.S. equity market. The fund generally will invest at least 80% of its assets in the component securities of its underlying index and may invest up to 20% of its assets in certain futures, options and swap contracts, cash and cash equivalents.