Exhibit (12)

MARSHALL & ILSLEY CORPORATION

Computation of Ratio of Earnings to Fixed Charges

($000’s)

	Years Ended December 31,
	2006		2005		2004		2003		2002
Earnings:
Earnings before income taxes, extraordinary items and cumulative effect of changes in accounting principles	$	1,195,632	$	1,057,654	$	911,840	$	724,507	$	683,364
Fixed charges, excluding interest on deposits		692,646		463,209		281,244		267,379		301,518
Earnings including fixed charges but excluding interest on deposits		1,888,278		1,520,863		1,193,084		991,886		984,882
Interest on deposits		1,058,713		544,920		276,102		228,216		283,385
Earnings including fixed charges and interest on deposits	$	2,946,991	$	2,065,783	$	1,469,186	$	1,220,102	$	1,268,267
Fixed Charges:
Interest Expense:
Short-term borrowings	$	186,863	$	106,333	$	61,256	$	81,070	$	150,310
Long-term borrowings		476,625		330,144		196,440		163,348		127,343
One-third of rental expense for all operating leases (the amount deemed representative of the interest factor)		29,158		26,732		23,548		22,961		23,865
Fixed charges excluding interest on deposits		692,646		463,209		281,244		267,379		301,518
Interest on deposits		1,058,713		544,920		276,102		228,216		283,385
Fixed charges including interest on deposits	$	1,751,359	$	1,008,129	$	557,346	$	495,595	$	584,903
Ratio of Earnings to Fixed Charges:
Excluding interest on deposits		2.73 x		3.28 x		4.24 x		3.71 x		3.27 x
Including interest on deposits		1.68 x		2.05 x		2.64 x		2.46 x		2.17 x