The fund normally invests at least 80% of the fund's net assets in municipal securities whose interest is exempt from regular federal income tax, but not necessarily the federal alternative minimum tax (AMT). It invests up to 35% of the fund's total assets in below investment-grade municipal securities. The fund invests principally in municipal securities of states, territories and possessions of the United States whose interest is exempt from regular federal income tax, but not necessarily federal AMT.