The investment seeks to track the investment results of the Morningstar® US Mid Cap IndexSM composed of mid-capitalization U.S. equities. 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. The underlying index measures the performance of stocks issued by mid-capitalization companies that have exhibited both ?growth? and ?value? characteristics as determined by Morningstar, Inc.?s (?Morningstar? or the ?index provider?) proprietary index methodology.