The fund normally invests at least 80% of its net assets in municipal securities such that the interest on each bond is exempt from U.S. federal income taxes and the federal alternative minimum tax ("AMT"). It primarily invests in U.S. dollar-denominated investment-grade short-term fixed- and floating-rate municipal securities with remaining maturities of five years or less, such as municipal bonds, municipal notes and variable rate demand obligations, as well as money market instruments and registered investment companies. The fund is an actively managed exchange-traded fund ("ETF").