Marshall & Ilsley (MI)

MARSHALL & ILSLEY CORPORATION ANNOUNCES $350 MILLION
DISCRETIONARY EQUITY ISSUANCE PLAN

Milwaukee, Wis. – May 19, 2009 – Marshall & Ilsley Corporation (NYSE: MI) (M&I) announced today that it has commenced a discretionary equity issuance plan  pursuant to which it will offer shares of its common stock having aggregate sales proceeds of up to $350 million. Sales of the shares of common stock, if any, will be made by means of ordinary brokers’ transactions on the New York Stock Exchange or otherwise at then prevailing market prices.  Morgan Stanley & Co. Incorporated will act as M&I’s sales agent for the offering. M&I has filed a prospectus supplement to its existing automatic shelf registration statement on file with the Securities and Exchange Commission (SEC) in connection with the offering.

M&I intends to use the net proceeds of any sales under the program for general corporate purposes and may contribute some portion of the net proceeds to the capital of its subsidiaries, which will use these contributions for their general corporate purposes.

To the extent that M&I’s Board of Directors determines at a future date that it is in the best interests of M&I and its shareholders to do so, M&I may elect to repurchase a portion of its Senior Preferred Stock, Series B issued to the United States Department of the Treasury as part of its Capital Purchase Program with all or a portion of the remaining net proceeds of this offering. Any such repurchase would be subject to consultation with and approval by M&I’s banking regulators. In the event that M&I chooses to seek such approval, there can be no assurance that such approval would be granted.

This press release does not constitute an offer to sell or a solicitation of an offer to buy any securities, nor shall there be any sale of these securities in any state or jurisdiction in which such

an offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

The offering will be made pursuant to M&I’s effective shelf registration statement filed with the SEC.  Investors should read the prospectus supplement and the accompanying prospectus for more complete information about M&I and the offering.  These documents can be obtained free of charge by visiting IDEA on the SEC’s website at www.sec.gov.  Alternatively, copies may be obtained from Morgan Stanley & Co. Incorporated, 180 Varick Street, Second Floor, New York, New York 10014, Attention:  Prospectus Department, Toll Free (866) 718-1649, or by email at prospectus@morganstanley.com.