Table of Contents


EXHIBIT12




MARSHALL
      & ILSLEY CORPORATIONComputation
      ofRatio
      of Earnings to Fixed Charges($000's)Three
      MonthsEnded
      March 31,
                                                                                                                
                                                                                                                
                                                                                                                Years
      Ended December 31,2009
                                                                                                                
                                                                                                                
                                                                                                                2008
                                                                                                                
                                                                                                                
                                                                                                                2007
                                                                                                                
                                                                                                                
                                                                                                                2006
                                                                                                                
                                                                                                                
                                                                                                                2005
                                                                                                                
                                                                                                                
                                                                                                                2004Excluding
      Interest on Deposits:Income
      (loss) from continuing operations before income taxes attributable to
      Marshall & Ilsley Corporation
                                                                                                                
                                                                                                                $
                                                                                                                (244,629
                                                                                                                )
                                                                                                                
                                                                                                                $
                                                                                                                (2,502,117
                                                                                                                )
                                                                                                                
                                                                                                                $
                                                                                                                713,475
                                                                                                                
                                                                                                                
                                                                                                                $
                                                                                                                960,416
                                                                                                                
                                                                                                                
                                                                                                                $
                                                                                                                869,990
                                                                                                                
                                                                                                                
                                                                                                                $
                                                                                                                791,156Less:  Net
      income attributable to noncontrolling interests
                                                                                                                
                                                                                                                
                                                                                                                (319
                                                                                                                )
                                                                                                                
                                                                                                                
                                                                                                                (870
                                                                                                                )
                                                                                                                
                                                                                                                
                                                                                                                (2,895
                                                                                                                )
                                                                                                                
                                                                                                                
                                                                                                                (5,267
                                                                                                                )
                                                                                                                
                                                                                                                
                                                                                                                (5,207
                                                                                                                )
                                                                                                                
                                                                                                                
                                                                                                                (5,162
                                                                                                                )Income
      (loss) from continuing operations before income taxes
                                                                                                                
                                                                                                                $
                                                                                                                (244,948
                                                                                                                )
                                                                                                                
                                                                                                                $
                                                                                                                (2,502,987
                                                                                                                )
                                                                                                                
                                                                                                                $
                                                                                                                710,580
                                                                                                                
                                                                                                                
                                                                                                                $
                                                                                                                955,149
                                                                                                                
                                                                                                                
                                                                                                                $
                                                                                                                864,783
                                                                                                                
                                                                                                                
                                                                                                                $
                                                                                                                785,994Fixed
      charges:Interest
      expense - short-term borrowings
                                                                                                                
                                                                                                                
                                                                                                                3,992
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                139,627
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                236,671
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                186,746
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                106,220
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                61,144Interest
      expense - long-term borrowings
                                                                                                                
                                                                                                                
                                                                                                                99,956
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                454,413
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                585,025
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                476,540
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                329,876
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                196,1601/3
      of rent expense (1)
                                                                                                                
                                                                                                                
                                                                                                                3,106
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                12,423
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                9,724
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                7,917
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                6,138
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                5,576Fixed
      charges
                                                                                                                
                                                                                                                
                                                                                                                107,054
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                606,463
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                831,420
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                671,203
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                442,234
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                262,880Preferred
      stock dividends (2)
                                                                                                                
                                                                                                                
                                                                                                                38,398
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                19,595
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                -
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                -
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                -
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                -Fixed
      charges and preferred stock dividends
                                                                                                                
                                                                                                                
                                                                                                                145,452
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                626,058
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                831,420
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                671,203
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                442,234
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                262,880Earnings
                                                                                                                
                                                                                                                $
                                                                                                                (137,894
                                                                                                                )
                                                                                                                
                                                                                                                $
                                                                                                                (1,896,524
                                                                                                                )
                                                                                                                
                                                                                                                $
                                                                                                                1,542,000
                                                                                                                
                                                                                                                
                                                                                                                $
                                                                                                                1,626,352
                                                                                                                
                                                                                                                
                                                                                                                $
                                                                                                                1,307,017
                                                                                                                
                                                                                                                
                                                                                                                $
                                                                                                                1,048,874Ratio
      of earnings to fixed charges (3)
                                                                                                                
                                                                                                                n.m.
                                                                                                                
                                                                                                                
                                                                                                                n.m.
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                1.85
                                                                                                                x
                                                                                                                
                                                                                                                
                                                                                                                2.42
                                                                                                                x
                                                                                                                
                                                                                                                
                                                                                                                2.96
                                                                                                                x
                                                                                                                
                                                                                                                
                                                                                                                3.99
                                                                                                                xRatio
      of earnings to fixed charges and preferred dividends (3)
                                                                                                                
                                                                                                                n.m.
                                                                                                                
                                                                                                                
                                                                                                                n.m.
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                1.85
                                                                                                                x
                                                                                                                
                                                                                                                
                                                                                                                2.42
                                                                                                                x
                                                                                                                
                                                                                                                
                                                                                                                2.96
                                                                                                                x
                                                                                                                
                                                                                                                
                                                                                                                3.99
                                                                                                                xIncluding
      Interest on Deposits:Income
      (loss) from continuing operations before income taxes
                                                                                                                
                                                                                                                $
                                                                                                                (244,948
                                                                                                                )
                                                                                                                
                                                                                                                $
                                                                                                                (2,502,987
                                                                                                                )
                                                                                                                
                                                                                                                $
                                                                                                                710,580
                                                                                                                
                                                                                                                
                                                                                                                $
                                                                                                                955,149
                                                                                                                
                                                                                                                
                                                                                                                $
                                                                                                                864,783
                                                                                                                
                                                                                                                
                                                                                                                $
                                                                                                                785,994Fixed
      charges:Fixed
      charges
                                                                                                                
                                                                                                                
                                                                                                                107,054
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                606,463
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                831,420
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                671,203
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                442,234
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                262,880Interest
      expense - deposits
                                                                                                                
                                                                                                                
                                                                                                                138,089
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                902,944
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                1,231,252
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                1,083,392
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                562,552
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                281,271Fixed
      charges
                                                                                                                
                                                                                                                
                                                                                                                245,143
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                1,509,407
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                2,062,672
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                1,754,595
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                1,004,786
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                544,151Preferred
      stock dividends (2)
                                                                                                                
                                                                                                                
                                                                                                                38,398
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                19,595
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                -
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                -
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                -
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                -Fixed
      charges and preferred stock dividends
                                                                                                                
                                                                                                                
                                                                                                                283,541
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                1,529,002
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                2,062,672
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                1,754,595
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                1,004,786
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                544,151Earnings
                                                                                                                
                                                                                                                $
                                                                                                                195
                                                                                                                
                                                                                                                
                                                                                                                $
                                                                                                                (993,580
                                                                                                                )
                                                                                                                
                                                                                                                $
                                                                                                                2,773,252
                                                                                                                
                                                                                                                
                                                                                                                $
                                                                                                                2,709,744
                                                                                                                
                                                                                                                
                                                                                                                $
                                                                                                                1,869,569
                                                                                                                
                                                                                                                
                                                                                                                $
                                                                                                                1,330,145Ratio
      of earnings to fixed charges (3)
                                                                                                                
                                                                                                                
                                                                                                                0.00
                                                                                                                x
                                                                                                                
                                                                                                                n.m.
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                1.34
                                                                                                                x
                                                                                                                
                                                                                                                
                                                                                                                1.54
                                                                                                                x
                                                                                                                
                                                                                                                
                                                                                                                1.86
                                                                                                                x
                                                                                                                
                                                                                                                
                                                                                                                2.44
                                                                                                                xRatio
      of earnings to fixed charges and preferred dividends (3)
                                                                                                                
                                                                                                                
                                                                                                                0.00
                                                                                                                x
                                                                                                                
                                                                                                                n.m.
                                                                                                                
                                                                                                                
                                                                                                                
                                                                                                                1.34
                                                                                                                x
                                                                                                                
                                                                                                                
                                                                                                                1.54
                                                                                                                x
                                                                                                                
                                                                                                                
                                                                                                                1.86
                                                                                                                x
                                                                                                                
                                                                                                                
                                                                                                                2.44
                                                                                                                x(1)
      Represents one-third of rental expense for all operating leases (the
      amount deemed representative of the interest factor).(2)
      Assuming a Federal income tax rate of 35%.(3)
      The ratio of earnings to fixed charges was less than one-to-one for the
      three months ended March 31, 2009 and for the year ended December 31,
      2008.
   57