Strategy. The fund invests in municipal and other debt securities with an emphasis on high-yield securities. A high-yield security is one that has been rated below investment-grade, or determined by the investment advisor to be of similar quality. Under normal market conditions, the portfolio managers invest at least 80% of the funds net assets 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 portfolio managers seek to invest in securities that will result in a high yield for the fund. To accomplish this, the portfolio managers buy securities that are rated below investment-grade, including so-called junk bonds and bonds that are … Show more… The fund invests in municipal and other debt securities with an emphasis on high-yield securities. A high-yield security is one that has been rated below investment-grade, or determined by the investment advisor to be of similar quality. Under normal market conditions, the portfolio managers invest at least 80% of the funds net assets 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 portfolio managers seek to invest in securities that will result in a high yield for the fund. To accomplish this, the portfolio managers buy securities that are rated below investment-grade, including so-called junk bonds and 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 objectives of the fund. The managers typically buy long-term and intermediate-term municipal securities, but may purchase municipal securities of any duration. The managers attempt to keep the weighted average maturity of the fund at 10 years or longer. Although the fund invests principally for 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. When determining whether to sell a security, 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. Show less