Strategy. Under normal market conditions, the Fund seeks to achieve its investment objectives by investing at least 80% of its net assets (plus any borrowings for investment purposes) in municipal debt securities that pay interest that is exempt from federal income taxes. Municipal securities are generally issued by or on behalf of states, territories or possessions of the United States and the District of Columbia and their political subdivisions, agencies, authorities and other instrumentalities. The types of municipal securities in which the Fund may invest include municipal lease obligations (and certificates of participation in such obligations), municipal general obligation bonds, municipal revenue bonds, municipal notes, municipal cash equivalents, private activity bonds (including without limitation industrial development bonds), zero coupon bonds and … Show more… Under normal market conditions, the Fund seeks to achieve its investment objectives by investing at least 80% of its net assets (plus any borrowings for investment purposes) in municipal debt securities that pay interest that is exempt from federal income taxes. Municipal securities are generally issued by or on behalf of states, territories or possessions of the United States and the District of Columbia and their political subdivisions, agencies, authorities and other instrumentalities. The types of municipal securities in which the Fund may invest include municipal lease obligations (and certificates of participation in such obligations), municipal general obligation bonds, municipal revenue bonds, municipal notes, municipal cash equivalents, private activity bonds (including without limitation industrial development bonds), zero coupon bonds and pre-refunded and escrowed-to-maturity bonds. In addition, municipal securities include securities issued by tender option bond ( TOB ) trusts and custodial receipt trusts. The Fund may also invest up to 20% of its net assets (measured by notional value) in derivative instruments, other than TOB and custodial receipts trusts, to obtain net long or short exposures to selected interest rates or to hedge risks, including interest rate risks and credit risks, associated with the Funds portfolio investments. The Fund may invest in municipal securities of any duration or maturity. The Funds investment advisor selects the securities for the Fund by implementing an investment process that is comprised of the following components: 1. Total return scenario analysis: Evaluate individual bonds and portfolios of securities that are exposed to interest rate, yield curve and credit spread movements or shifts. 2. Sector analysis: Perform top-down review of core sectors based on bottom-up analysis of individual credits to determine the sectors in which the Fund will be overweight, neutral weight and underweight. 3. New issue credit analysis: Evaluate new bond offerings to determine portfolio suitability based on fundamental credit research on each borrower and individual bond security features. 4. Trading: Analyze how a bond might trade in the secondary market by reviewing total bond issuance size, underwriter willingness to make secondary markets and bond structural features, such as coupon, maturity, call dates and sinking fund payments. 5. Surveillance: Analyze holdings on a systematic basis to monitor any changes in credit trend. The Funds advisor monitors the credit rating momentum of each bond. 6. Performance attribution: Perform granular total return analysis by reviewing key portfolio attributes such as duration, credit rating, sector and state. The portfolios performance is also compared to various benchmarks. The Fund invests at least 65% of its net assets in investment grade securities, which are securities that are rated at the time of investment in one of the four highest credit quality categories by at least one nationally recognized statistical rating organization ( "NRSRO" ) rating that security or, if unrated, determined by the Funds investment advisor to be of comparable quality. The Fund considers pre-refunded or escrowed-to-maturity bonds, regardless of rating, to be investment grade securities. The Fund may invest up to 35% of its net assets in securities that are, at the time of investment, rated below investment grade (or securities that are unrated and determined by the Funds investment advisor to be of comparable quality), commonly referred to as high yield or junk bonds. When determining whether a security is classified as below investment grade, the Fund's investment advisor will consider the highest rating available from an NRSRO. Additionally, for newly-issued securities, the Fund may consider an expected rating provided by an NRSRO as if it were a final rating. If, subsequent to purchase by the Fund, a security held by the Fund experiences a decline in credit quality and falls below investment grade, the Fund may continue to hold the security and it will not cause the Fund to violate the 35% investment limitation; however, the security will be taken into account for purposes of determining whether purchases of additional securities will cause the Fund to violate such limitation. Furthermore, the Fund may invest up to 10% of its net assets in taxable municipal securities. The Fund may invest in fixed and floating-rate securities. Certain investors may be subject to federal alternative minimum tax on dividends attributable to Fund investments in private activity bonds. Additionally, the Fund may invest up to 100% of its net assets in municipal securities that pay interest that generates income subject to federal alternative minimum tax. The Fund is classified as non-diversified under the Investment Company Act of 1940, as amended (the 1940 Act ). Show less