MMIN offers an active management perspective on the US investment-grade municipal bond space. The portfolio includes bonds of varying maturities (dollar-weighted average duration of 3-15 years), issued by at least 15 different states and encompassing at least 10 sectors, with no more than 30% of the securities from a single state. The fund selects bonds covered by an insurance policy, which guarantees principal and interest payments but lowers yield, and debt securities whose interest is exempt from federal Income tax.