Rule 424(b)(2) File No. 333-33814 Pricing Supplement #123 dated May 2, 2005 to the Prospectus Dated April 12, 2000 and Prospectus Supplement Dated October 21, 2003 Marshall & Ilsley Corporation MiNotes SM Due from 9 Months to 30 Years Trade Date: May 2, 2005 Issue Price: 100% Original Issue Date: May 5, 2005 Principal Amount: $234,000 Maturity Date: May 17, 2010 Interest Rate: 4.25% Interest Payment Dates: 05/15/05 and monthly thereafter Purchasing Agent acting as Principal: Merrill Lynch & Co. Purchasing Agent Commission: 1.00% Proceeds Before expenses: 99.00% ($231,660.00) Survivor's Option: Yes Redemption or Repayment: At Maturity Redemption/Repayment Terms: Not Applicable Minimum Denomination: $1,000 minimum investment with increments of $1,000 CUSIP No.: 57183MFH8 Original Issue Discount: No Notes: All trades settle without accrued interest and clear SDFS: DTC Book-Entry only Merrill Lynch DTC Participant Number: 161