Marshall & Ilsley
Marshall & Ilsley was a Milwaukee-based American bank and diversified financial services company that became part of Bank of Montreal's U.S. banking operations.
Last updated November 4, 2026
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Overview
Marshall & Ilsley Corporation, widely known as M&I Bank, was a Wisconsin-based banking and financial services organization whose origins dated to 1847. Samuel Marshall began the business as an exchange brokerage in Milwaukee, operating from a downtown cobbler's shop at a time when Wisconsin did not yet permit state-chartered banks. Although the early enterprise was not initially a formally chartered bank, it offered banking-related services including deposits and loans. Charles Ilsley joined Marshall as a partner in 1849, and the business adopted the Marshall & Ilsley name in 1850. After Wisconsin authorized state-chartered banking in 1852, the company obtained the first such charter, for a bank in Madison. For much of its early history, Marshall & Ilsley was associated with conservative banking practices. That posture helped it withstand major periods of financial stress, including the Panic of 1893 and the stock-market crash of 1929. The company nevertheless remained geographically concentrated for many decades. After selling its Madison bank in the late nineteenth century, it conducted business primarily in Milwaukee for more than sixty years. The organization entered a more expansive phase in the twentieth century. In 1958, after operating as a partnership for more than a century, it reorganized as the leading subsidiary of Bank Stock Corporation of Milwaukee. The new corporate structure acquired Northern Bank and Bank of Commerce, while the constituent banks initially retained their own names and operating locations. Following regulatory changes and the forced divestiture of Bank of Commerce in 1969, Bank Stock Corporation received greater scope to acquire banks in markets without competing institutions and to establish branches near Milwaukee. The parent company adopted the Marshall & Ilsley Corporation name in 1971. M&I expanded beyond Wisconsin in 1986 through the acquisition of Arizona-based Thunderbird Bank. It later pursued additional consolidation opportunities, including an unsuccessful 1987 hostile bid for Milwaukee-based Marine Corporation, the parent of Marine Bank. M&I did complete the smaller acquisition of Central Wisconsin Bankshares in the same period. Its 1993 merger with Valley Bancorporation significantly enlarged its Wisconsin network, adding 155 Valley Bank locations, including one in Illinois, in a stock transaction valued at approximately $875 million at announcement. During the 2000s, M&I broadened its geographic footprint and its financial-services capabilities. It agreed in 2006 to acquire United Heritage Bankshares of Florida, adding a presence in the Orlando area. Its technology-services subsidiary, originally known as Marshall and Ilsley Data Services and later Metavante Corporation, was spun off in 2007 as a separately traded public company. M&I also completed the acquisition of First Indiana in 2008, adding 32 central-Indiana locations, and acquired Southwest Bank in St. Louis in 2010. The financial crisis placed pressure on the bank. In 2009, M&I was identified among large U.S. lenders with a significant proportion of nonperforming loans. By 2008, the company reported approximately $63.5 billion in assets and more than 250 branches. Its network by the time of its acquisition covered Wisconsin and several out-of-state markets, including Arizona, Florida, Indiana, Minnesota, Nevada, Missouri, and the Kansas City area. On December 17, 2010, Bank of Montreal agreed to acquire Marshall & Ilsley in an all-stock transaction valued at approximately $4.1 billion at announcement. The transaction was completed in July 2011 through BMO's U.S. subsidiary. M&I's banking entities were subsequently combined with Harris Bank, Bank of Montreal's existing U.S. subsidiary. The unified institution adopted the BMO Harris Bank name, with the branding transition completed on October 9, 2012. Marshall & Ilsley therefore ceased to operate as an independent banking brand, while its branches, customers, employe…
History
Marshall & Ilsley's history began in 1847, when Pennsylvania native Samuel Marshall established an exchange brokerage in Milwaukee. Because Wisconsin had not yet authorized state-chartered banks, the enterprise provided banking services without initially operating as a state-chartered bank. Charles Ilsley, a Maine native, joined Marshall in 1849, and the firm took the Marshall & Ilsley name the following year. In 1852, after Wisconsin permitted state-chartered banking, M&I obtained the first charter of this type for a Madison bank. The institution spent much of its first century emphasizing financial conservatism. It survived the Panic of 1893 and remained one of the few major Wisconsin banks to survive the banking stresses associated with the 1929 stock-market crash. Its geographic reach, however, remained limited. After selling its Madison operation in the late nineteenth century, M&I focused on Milwaukee for more than sixty years. A structural transformation began in 1958, when the partnership reorganized as the leading subsidiary of Bank Stock Corporation of Milwaukee. The new parent acquired Northern Bank and Bank of Commerce, initially allowing the three institutions to preserve their individual names and headquarters. Regulatory requirements led to the sale of Bank of Commerce in 1969, but also permitted Bank Stock Corporation to acquire banks in markets without competing institutions and to expand branches near Milwaukee. The parent changed its name to Marshall & Ilsley Corporation in 1971. M&I began a more ambitious regional expansion in 1986 with the purchase of Thunderbird Bank in Arizona. It unsuccessfully attempted to acquire Marine Corporation, the Milwaukee parent of Marine Bank, through a hostile bid in 1987; Marine instead accepted an offer from Banc One Corporation. M&I did acquire Central Wisconsin Bankshares of Wausau in a smaller transaction. In 1993, its merger with Valley Bancorporation added 155 Valley Bank offices and materially strengthened M&I's Wisconsin network. The company continued expanding during the 2000s. It agreed to acquire United Heritage Bankshares in Florida in 2006, spun off its technology-services subsidiary as Metavante in 2007, and completed the acquisition of First Indiana in 2008. First Indiana brought 32 central-Indiana locations. M&I also acquired Southwest Bank in St. Louis in 2010. By 2008, the company had approximately $63.5 billion in assets and more than 250 branches. The global financial crisis exposed weaknesses in the bank's loan book. In 2009, reports identified M&I among major U.S. lenders with nonperforming loans above five percent, a level considered potentially capable of eroding a bank's equity. The company remained a sizeable multi-state institution, with operations spanning Wisconsin, Arizona, Florida, Indiana, Minnesota, Nevada, Missouri, and the Kansas City area. On December 17, 2010, Bank of Montreal agreed to buy M&I in an all-stock transaction valued at about $4.1 billion at announcement. BMO completed the acquisition through its U.S. subsidiary in July 2011. M&I's banking entities were later merged into Harris Bank. The combined organization was branded BMO Harris Bank, and the transition from the M&I and Harris names was completed on October 9, 2012. This ended Marshall & Ilsley's independent existence as a bank brand, although its operations became part of BMO's U.S. banking business.
- 2012
M&I brand retired through BMO Harris combination
[1]M&I's banking operations were combined with Harris Bank, with the BMO Harris Bank branding transition completed in October.
- 2010
Bank of Montreal acquisition announced
[1]BMO agreed to acquire M&I in an all-stock transaction valued at approximately $4.1 billion at announcement.
- 2008
First Indiana acquisition completed
[2]M&I completed the acquisition of First Indiana and added 32 central-Indiana branches.
- 2007
Metavante spin-off
[1]The former Marshall and Ilsley Data Services technology subsidiary became the separately traded Metavante Corporation.
- 1993
Valley Bancorporation merger
[1]The merger added 155 Valley Bank locations and expanded M&I's Wisconsin presence.
- 1986
Expansion into Arizona
[1]M&I acquired Arizona-based Thunderbird Bank, its first major expansion outside Wisconsin.
- 1971
Bank Stock Corporation becomes Marshall & Ilsley Corporation
[1]The parent company adopted the Marshall & Ilsley Corporation name.
- 1958
Reorganization under Bank Stock Corporation
[1]M&I reorganized from a partnership into the leading subsidiary of Bank Stock Corporation of Milwaukee and became associated with Northern Bank and Bank of Commerce.
- 1852
First Wisconsin state bank charter
[1]After state-chartered banking became permissible, M&I obtained the first such charter for a Madison bank.
- 1850
Marshall & Ilsley name adopted
[1]The partnership began operating under the Marshall & Ilsley name.
Products and positioning
A conservative, relationship-oriented regional bank that developed from a Milwaukee institution into a multi-state U.S. banking and financial-services company.
Consumer banking
Retail banking
M&I Bank operated a branch-based retail banking business offering deposit accounts, loans, and routine banking services to consumers and local communities. Its historical strength was concentrated in Wisconsin, although the network later extended into several other U.S. states and metropolitan areas.
Commercial banking
Commercial and business banking
The company provided banking and credit services to businesses and commercial customers through its regional branch network. These activities formed a core part of M&I's identity as a full-service regional bank rather than a purely consumer-focused institution.
Financial technology services
Marshall and Ilsley Data Services / Metavante
M&I's technology-services operation, originally known as Marshall and Ilsley Data Services, supported financial institutions with processing and related technology capabilities. It was separated from the bank in 2007 and became Metavante Corporation, an independently traded company.
Brand decisions
2010
Agree to acquisition by Bank of MontrealM&ABackground
M&I remained a large multi-state bank but faced pressure associated with the financial crisis and elevated nonperforming loans.
Action taken
M&I agreed to an all-stock acquisition by Bank of Montreal, valued at approximately $4.1 billion at announcement.
Aftermath
BMO completed the purchase in 2011 and subsequently combined M&I's banking entities with Harris Bank under the BMO Harris Bank name.
Transaction value. $4.1 billion approximate announced value (December 17, 2010 announcement)
2007
Separate Metavante as an independent public companyStrategyBackground
M&I had developed a technology-services subsidiary under the Marshall and Ilsley Data Services name.
Action taken
The subsidiary was spun off as Metavante Corporation and began trading separately on the New York Stock Exchange.
Aftermath
The separation made the technology business an independent public company rather than a wholly owned M&I operation.
Sources2 sources
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