Strategy. The fund invests in municipal and other debt securities. Under normal market conditions, the portfolio managers invest at least 80% of the funds net assets, plus borrowings for investment purposes, in municipal securities with interest payments exempt from federal income tax. Some of these investments in municipal securities are not necessarily exempt from the federal alternative minimum tax. The fund principally invests in investment-grade debt securities but may invest in high-yield securities (junk bonds). A high-yield security is one that has been rated below investment-grade or determined by the investment advisor to be of similar quality, including bonds that are in technical or monetary default. Issuers of these securities often have short financial histories or have questionable credit or have … Show more… The fund invests in municipal and other debt securities. Under normal market conditions, the portfolio managers invest at least 80% of the funds net assets, plus borrowings for investment purposes, in municipal securities with interest payments exempt from federal income tax. Some of these investments in municipal securities are not necessarily exempt from the federal alternative minimum tax. The fund principally invests in investment-grade debt securities but may invest in high-yield securities (junk bonds). A high-yield security is one that has been rated below investment-grade or determined by the investment advisor to be of similar quality, including bonds that are in technical or monetary default. Issuers of these securities often have short financial histories or have questionable credit or have had and may continue to have problems making interest and principal payments. The portfolio managers also may buy unrated securities if they determine such securities meet the investment objective of the fund. The fund may purchase debt securities of any duration, and the average duration of the fund will vary based on the portfolio managers forecast of interest rates. Although the fund seeks current income, it also employs techniques designed to realize capital appreciation. For example, the portfolio managers may select bonds with maturities and coupon rates that position the fund for potential capital appreciation for a variety of reasons, including their view on the direction of future interest-rate movements and the potential for a credit upgrade. The fund is an actively managed exchange-traded fund (ETF) that does not seek to replicate the performance of a specified index. When deciding whether to buy or sell a security, and how and when to implement a trade, portfolio managers consider, among other things, current and anticipated changes in interest rates, the credit quality of a particular issuer, comparable alternatives, general market conditions and any other factor deemed relevant by the portfolio managers. They may also consider the expected implementation costs and tax consequences of the trade in an attempt to gain trading efficiencies, avoid unnecessary risk, minimize tax impact, and/or enhance fund performance. Show less