Nuveen Premium Income Municipal Fund, Inc. (the Fund) is a closed-end management investment company. The Fund seeks to provide current income exempt from regular federal income tax by investing primarily in a portfolio of municipal obligations issued by state and local government authorities or certain United States territories. It invests primarily in tax-exempt municipal securities rated within the four highest grades (Baa/BBB or better). Up to 20% of the Fund's assets may be invested in unrated municipal obligations considered to be of comparable quality. The Fund invests in various sectors, which include healthcare, transportation, utilities, and education and civic organizations. The Fund's adviser is Nuveen Asset Management, a wholly owned subsidiary of Nuveen Investments, Inc.