The fund normally invests at least 80% of the fund's net assets in municipal securities whose interest is exempt from federal income tax, but not necessarily federal alternative minimum tax (AMT). It invests up to 20% of the fund's total assets in securities whose interest is subject to federal AMT. While the fund may purchase securities of any maturity, under normal circumstances, the advisor expects the fund's dollar-weighted average effective maturity to be 1 year or less.