Strategy. Under normal market conditions, the fund invests at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in municipal bonds. The fund considers municipal bonds to be comprised of securities the income from which is exempt from regular income tax and includes securities that generate income subject to the alternative minimum tax (AMT). The manager normally invests primarily in medium- and lower-quality municipal securities rated A and below by Moodys Investors Service, Inc. (Moodys), S&P Global Ratings (S&P), and Fitch Ratings, Inc. (Fitch Ratings), or their unrated equivalents. The fund may buy bonds of any maturity. However, the fund will not invest more than 5% of its total assets in securities rated lower than … Show more… Under normal market conditions, the fund invests at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in municipal bonds. The fund considers municipal bonds to be comprised of securities the income from which is exempt from regular income tax and includes securities that generate income subject to the alternative minimum tax (AMT). The manager normally invests primarily in medium- and lower-quality municipal securities rated A and below by Moodys Investors Service, Inc. (Moodys), S&P Global Ratings (S&P), and Fitch Ratings, Inc. (Fitch Ratings), or their unrated equivalents. The fund may buy bonds of any maturity. However, the fund will not invest more than 5% of its total assets in securities rated lower than B. The funds investment policies are based on credit ratings at the time of purchase. Bonds that are rated at or below BB by S&P or Fitch or Ba by Moodys are considered junk bonds. Municipal bonds may be subject to the AMT and income may not be entirely tax-free to all investors. The fund may invest heavily in bonds from any given state or region. The fund may engage in derivative transactions to reduce risk and/or enhance investment returns. Derivatives may include futures contracts on debt securities and debt securities indexes; options on futures, debt securities and debt indexes; and inverse floating-rate securities. The fund may also use tender option bond transactions to seek to enhance potential gains. The fund will look through to the underlying municipal bonds held by a tender option bond trust for purposes of the funds 80% policy. The fund may leverage its assets through the use of proceeds received as a result of tender option bond transactions. The fund may contribute up to 15% of its holdings in municipal securities to tender option bond transactions. The manager looks for undervalued bonds, based on both broad and security-specific factors such as issuer creditworthiness, bond structure, and general credit trends, and uses detailed analysis of an appropriate index to model portfolio performance and composition. The fund may invest in general obligation bonds, however, in general, the manager favors bonds backed by revenue from a specific public project or facility, such as a power plant (revenue bonds), which tend to offer higher yields than general obligation bonds. The manager also favors bonds that have limitations on early payoff (call protection), which can help minimize the potential effect of falling interest rates on the funds yield. The manager may implement short-term trading strategies to take advantage of pricing imbalances within the municipal bond market. For liquidity and flexibility, the fund may invest up to 20% of its net assets (plus any borrowings for investment purposes) in taxable and tax-free investment-grade short-term securities. Show less