Washington, D.C. 20549
Proxy Statement Pursuant to Section 14(a) of the Securities
Exchange Act of 1934 (Amendment No.   )
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o   Soliciting Material Pursuant to §240.14a-11(c) or §240.14a-12
Nuveen Insured Municipal Opportunity Fund, Inc. (NIO)
(Name of Registrant as Specified In Its Charter)
(Name of Person(s) Filing Proxy Statement, if other than the Registrant)
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Nuveen Closed-End Funds
Nuveen Insured Tax-Free Advantage Municipal Fund (NEA)
Nuveen Insured Municipal Opportunity Fund, Inc. (NIO)
Nuveen Premium Income Municipal Fund 2, Inc. (NPM)

333 West Wacker Drive
Chicago, Illinois 60606
Dear Shareholder:
We recently sent you proxy materials concerning an important proposal affecting your fund which was considered at the Special Shareholders Meeting held on Wednesday June 17, 2009. This proposal involves merging one or more Florida municipal bond closed-end funds into your national municipal bond closed-end fund. The meeting has been adjourned in order to allow more time for shareholders to cast their votes. The meeting will reconvene on Friday, July 24, 2009 at 4:00 p.m. Central time at the offices of Nuveen Investments, 333 West Wacker Drive, Chicago, IL. Our records indicate that we have not yet received your vote. If you have not yet voted, we urge you to vote as soon as possible in order to help your fund avoid the need for additional costly solicitation efforts.
ü   Your fund’s Board recommends you vote “FOR” each of the proposals.
ü   Proposals also have the support of a nationally-recognized proxy advisory firm.
Because over time Nuveen closed-end funds have seen increased institutional share ownership, the funds sought and received the support of ISS Governance Services Inc. (ISS). ISS is widely recognized as the leading independent proxy advisory firm in the nation. Its recommendations are relied upon by hundreds of major institutional investment firms, mutual funds, and other fiduciaries throughout the country. ISS recommends that its clients vote “FOR” each of the proposals contained in the proxy.
ü   Shareholders of the acquired funds have approved the proposals.
Shareholders of the Nuveen Florida closed-end fund or funds that are proposed to merge into your national closed-end fund have approved the merger with more than 80% of participating shares of each fund voting in favor of the merger.



The proxy materials we sent you contain important information regarding the proposals that you and other shareholders are being asked to consider. Please read the materials carefully. If you have any questions regarding the proposals, please call Computershare Fund Services, your Fund’s proxy agent, at 1-866-963-6132. Representatives are available Monday through Friday between the hours of 9:00 a.m. and 11:00 p.m. and Saturday from 12:00 p.m. to 6:00 p.m., Eastern Standard Time.
  1)   Automated Touch Tone Voting: Call the toll-free number listed on your proxy ballot and follow the recorded instructions.
  2)   Log on to the Internet address on your proxy ballot and follow the instructions.
  3)   Sign, date and return the enclosed proxy ballot using the enclosed postage-paid envelope.
Thank you for your prompt attention to this matter. If you have already voted, we appreciate your participation.