The investment seeks to track the investment results of the Russell Midcap Index, which measures the performance of the mid-capitalization sector of the U.S. equity market. The underlying index is a float-adjusted capitalization-weighted index of equity securities issued by the 806 smallest issuers in the Russell 1000 Index. The fund may use derivatives to gain or reduce exposure to the components of the underlying index or exposure to one or more market risk factors associated with such components.