Strategy. The Fund is an actively managed exchange-traded fund (ETF) that seeks to achieve its investment objective by investing, under normal market conditions, at least 80% of its net assets (plus any borrowings for investment purposes) in investments the income from which is exempt from federal income taxes (municipal securities) and in derivatives and other instruments that have economic characteristics similar to such securities. The municipal securities in which the Fund will invest include debt obligations of states, territories or possessions of the United States and the District of Columbia and their political subdivisions, agencies and instrumentalities, the interest on which is exempt from federal income tax, at the time of issuance, in the opinion of bond counsel or other counsel … Show more… The Fund is an actively managed exchange-traded fund (ETF) that seeks to achieve its investment objective by investing, under normal market conditions, at least 80% of its net assets (plus any borrowings for investment purposes) in investments the income from which is exempt from federal income taxes (municipal securities) and in derivatives and other instruments that have economic characteristics similar to such securities. The municipal securities in which the Fund will invest include debt obligations of states, territories or possessions of the United States and the District of Columbia and their political subdivisions, agencies and instrumentalities, the interest on which is exempt from federal income tax, at the time of issuance, in the opinion of bond counsel or other counsel to the issuers of such securities. The types of municipal securities in which the Fund will invest include fixed and variable rate securities. The Fund will normally maintain a weighted average portfolio duration of less than 7.5 years. Because of events affecting the bond markets and interest rate changes, the duration of the portfolio might not meet that target at all times. The foregoing duration target is not guaranteed and the portfolio managers may deviate from such target in their discretion. The Fund generally will invest at least 75% of its net assets in higher yielding municipal securities, specifically medium- and lower-grade municipal securities, which Invesco Advisers, Inc. (the Sub-Adviser) defines as (i) bonds rated BBB or lower by S&P Global Ratings (S&P), Baa or lower by Moodys Ratings (Moodys), or an equivalent rating by another nationally recognized statistical rating organization (NRSRO), or (ii) unrated securities determined by the Sub-Adviser to be of comparable quality, each at the time of purchase. Medium- and lower-grade securities are inclusive of some securities rated investment grade; however, many bonds in which the Fund will invest are rated below investment grade (commonly referred to as high yield securities or junk bonds with more speculative characteristics than investment grade securities). Below investment grade bonds are those rated below the four highest rating categories of S&P, Moodys, Fitch or another NRSRO (or, in the case of unrated securities, determined by the Sub-Adviser to be comparable to securities rated below investment-grade). At times, the market conditions in the municipal securities markets may be such that the Sub-Adviser may invest in higher-grade issues, particularly when the difference in returns between quality classifications is very narrow or when the Sub-Adviser expects interest rates to increase. Higher-grade securities are securities that are rated higher than medium- or lower-grade securities by Moodys, S&P, or Fitch, or considered by the Sub-Adviser to be of comparable quality, including municipal securities rated A-, SP-1 or higher by S&P or rated A3, MIG2, VMIG2 or higher by Moodys and tax-exempt commercial paper rated A-3 or higher by S&P or rated P-3 or higher by Moodys or unrated securities determined by the Sub-Adviser to be of comparable quality. The Fund may invest up to 10% of its total assets in defaulted or distressed municipal securities. If a security defaults or is downgraded subsequent to purchase by the Fund, the Sub-Adviser will determine in its discretion whether to hold or dispose of such security based on the Sub-Advisers assessment of the amount the Fund could expect to receive after holding the security for a longer term. The Fund may invest in inverse floating rate municipal obligations (also known as inverse floaters) issued in connection with tender option bond programs to generate leverage. Inverse floaters are variable rate debt instruments that pay interest at rates that move in the opposite direction of prevailing interest rates. An inverse floater is created when a fixed-rate municipal bond is contributed to a trust. The trust issues two separate classes of securities: short-term floating rate securities with a fixed principal amount that represent a senior interest in the underlying municipal bond, and the inverse floater that represents a residual, subordinate interest in the underlying municipal bond. The trust issues the short-term floating rate securities to third parties and the inverse floater to the Fund. When interest is paid on the underlying municipal bond to the trust, such proceeds are first used to pay interest owing to holders of the short-term floating rate securities, and any remaining amounts paid to the holder of the inverse floater. Accordingly, the amount of such interest paid to the Fund is inversely related to the rate of interest on the short-term floating rate securities. The Funds investments in inverse floating rate municipal obligations are included for purposes of the 80% policy described above. The Fund may invest in derivative instruments, including futures contracts and swap agreements. The Fund may use futures contracts, including interest rate futures, to reduce exposure to interest rate changes and to manage duration. The Fund may use swap agreements, including interest rate swaps, to hedge its exposure to interest rates. The Funds combined investment in inverse floating rate municipal obligations and derivatives will not exceed 15% of its net assets. Under normal market conditions, the Fund may invest all or a substantial portion of its assets in municipal securities that are subject to the federal alternative minimum tax (AMT). From time to time, the Fund temporarily may invest up to 10% of its net assets in tax exempt money market funds and such instruments will be treated as investments in municipal securities. The Fund may invest in municipal securities that are illiquid or thinly traded. The Fund may also invest in municipal securities that are subject to resale restrictions such as those contained in Rule 144A promulgated under the Securities Act of 1933, as amended (the Securities Act). The Funds investments may include municipal securities that do not produce immediate cash income, such as zero coupon securities and payment-in-kind securities. The Fund may purchase and sell municipal securities on a when-issued and delayed delivery basis, which means that the Fund may buy or sell a security with payment and delivery taking place in the future. The Fund can invest up to 25% of its total assets in municipal securities that are tobacco settlement revenue bonds and up to 25% of its total assets in municipal securities that are tobacco-related bonds without an appropriation pledge that make payments only from a state's interest in the Master Settlement Agreement (MSA). The MSA settled claims by 46 states and six other U.S. jurisdictions against the largest U.S. tobacco manufacturers. A number of the states have sold bonds that are backed by the future payments made by the tobacco manufacturers pursuant to the MSA. The Fund may invest in two types of those bonds: (i) bonds that make payments only from a state's interest in the MSA and (ii) bonds that make payments from both the MSA revenue and from an appropriation pledge by the state. An appropriation pledge requires the state to pass a specific periodic appropriation to make the payments and is generally not an unconditional guarantee of payment by a state. In managing the Fund, the Sub-Adviser uses a process for selecting securities for purchase and sale that is based on intensive credit research and involves extensive due diligence on each issuer. The credit research process utilized by the Sub-Adviser to implement the Funds investment strategy in pursuit of its investment objective considers factors that include, but are not limited to, an issuers operations and capital structure. The Fund has no policy limiting its investments in municipal securities whose issuers are located in the same state, territory or possession of the United States. However, it is not the present intention of the Fund to invest more than 25% of the value of its net assets in issuers located in the same state, territory or possession of the United States. Decisions to purchase or sell securities are determined by the relative value considerations of the portfolio managers that factor in economic and credit-related fundamentals, market supply and demand, market dislocations and situation-specific opportunities. The purchase or sale of securities may be related to a decision to alter the Funds macro risk exposure (such as duration, yield curve positioning and sector exposure), a need to limit or reduce the Funds exposure to a particular security or issuer, degradation of an issuers credit quality, or general liquidity needs of the Fund. The potential for realization of capital gains or losses resulting from possible changes in interest rates will not be a major consideration and frequency of portfolio turnover generally will not be a limiting factor if the Adviser considers it advantageous to purchase or sell securities. The Fund is non-diversified and therefore is not required to meet certain diversification requirements under the Investment Company Act of 1940, as amended (the 1940 Act). Show less