The investment seeks to track the performance of MSCI USA Risk Weighted Index that measures the performance of U.S. large- and mid-capitalization stocks with relatively smaller average market capitalization, before fees and expenses. The fund generally invests at least 90% of its assets in the securities of the underlying index or in depositary receipts representing securities in its underlying index. The MSCI USA Risk Weighted Index (the "underlying index") is based on a traditional market capitalization-weighted parent index, the MSCI USA Index, which includes U.S. large- and mid- capitalization stocks.