The investment seeks investment results that correspond generally to the price and yield performance, before fees and expenses, of the Barclays U.S. CMBS (ERISA Only) Index (the "underlying index"). The fund generally invests at least 90% of its assets in the securities of the underlying index and in investments that provide substantially similar exposure to the securities in the underlying index. The underlying index measures the performance of investment-grade commercial mortgage-backed securities ("CMBS"), which are classes of securities (known as "certificates") that represent interests in "pools" of commercial mortgages. The fund is non-diversified.