After World War II, Nesbitt Thomson expanded its operations to include chemicals, salt, steel, ships, farm machinery, retail stores, and a transcontinental natural gas pipeline.

In 2003 BMO Financial Group acquired Gerard Klauer Mattison (GKM), providing Harris Nesbitt with a U.S.-based equity research and institutional sales and trading platform.

GKM was founded in 1989 in New York as a boutique equity research and investment banking firm serving the institutional marketplace.

[2] In 2016 BMO Financial Group acquired the business of Greene Holcomb Fisher, a boutique M&A advisory firm based in Minneapolis.

[3] In August 2019 the US Securities and Exchange Commission fined BMO Capital Markets $3.9 million over its improper handling of “pre-released” American Depositary Receipts (ADRs).