Nuveen Insured Municipal Opportunity Fund, Inc. (the Fund) is a diversified closed-end management investment company. The Fund seeks to provide current income exempt from regular federal income tax, Each Fund seeks to provide current income exempt from regular federal income tax, and in the case of Insured Tax-Free Advantage (NEA) the alternative minimum tax applicable to individuals, by investing primarily in a diversified portfolio of municipal obligations issued by state and local government authorities or certain United States territories. It invests in sectors, such as transportation, utilities, healthcare and others. Nuveen Asset Management, a wholly owned subsidiary of Nuveen Investments, Inc., serves as the Fund’s investment adviser.