The investment seeks to maximize current income exempt from federal income tax, to the extent consistent with the preservation of capital. The fund normally invests substantially all of its net assets in municipal bonds that provide income exempt from federal income tax. It invests at least 75% of its assets in municipal bonds rated, at the time of purchase, A or higher or the unrated equivalent as determined by the sub-adviser. The dollar-weighted average maturity of the fund's portfolio normally exceeds ten years, but the fund may invest without regard to maturity.