The investment seeks to track the investment results of the Russell Midcap Growth Index, which measures the performance of the mid-capitalization growth sector of the U.S. equity market. The fund generally invests at least 90% of its assets in securities of the underlying index and in depositary receipts representing securities of the underlying index. It may invest the remainder of its assets in certain futures, options and swap contracts, cash and cash equivalents, as well as in securities not included in the underlying index, but which the advisor believes will help the fund track the underlying index.