The investment seeks maximum current income exempt from federal income taxes consistent with the preservation of capital and maintenance of liquidity. The fund normally invests at least 80% of its total assets in high-quality, short-term municipal securities that pay interest that is exempt from federal income tax, including the federal alternative minimum tax. The municipal securities in which the fund invests include variable rate demand notes (VRDNs) and tender option bonds (TOBs), which are floating rate instruments that provide the fund with the option to put or tender the VRDN or TOB back to the issuer at par.