To achieve investment objective, The Fund will normally invest at least 80 percent of its net assets (plus borrowings for investment purposes) in securities of the Index, which is comprised of tax-exempt municipal bond closed-end funds. Because the Index is comprised of securities issued by other investment companies (as opposed to operating companies), the Fund operates in a manner that is commonly referred to as a fund of funds, meaning that it invests its assets in shares of funds that are included in the Index. The Index seeks to measure the performance of the common stock (or its equivalent) of a select group of 30 U.S. exchange-listed municipal bond closed-end funds (the Underlying Funds), as selected and ranked according to factors employed by the Index methodology that are designed to result in a portfolio that produces high current income, generally exempt from regular U.S. federal income taxes, and that is intended to be distributed on a monthly basis. By tracking the Index, the Fund seeks to provide high monthly income through exposure to municipal bond closed-end funds and may also have capital appreciation potential by seeking Underlying Funds that are trading at a discount to net asset value (the Methodology).