The changing of the guard in the generation of Big Five bank CEOs who steered their institutions through the financial crisis is complete.

BMO Financial Group (BMO.TO) announced Friday its chief executive officer, Bill Downe, will retire effective October 31. He will be replaced by chief operating officer Darryl White on November 1.

"Darryl White's leadership has been steadfast and successful at every juncture of his banking career and he will maintain and build on our positive momentum," said BMO Chairman Robert Prichard in a statement. "He is a natural and authentic leader and the right person to lead the bank in a time of change in the wider economy."

Downe was appointed CEO of the bank in March 2007 after working his way up the ranks since joining BMO in 1983. Arguably, his signature move as CEO was the US$4.1-billion takeover of Milwaukee-based Marshall & Ilsley Corporation in 2010.

"I have complete confidence in Darryl to continue to build on our bank's success," Downe said in a statement. "In the coming months I look forward to working closely with him to ensure a smooth transition. The bank is very well positioned and the timing is right for BMO and its customers."

White previously served as head of BMO Capital Markets prior to his appointment as COO in November.

"I am energized by the opportunities ahead both for BMO's customers and for our employees. Bill Downe's leadership has been extraordinary on every level," White said in a statement. ""I am deeply appreciative of the board's confidence and look forward to spending the remainder of the fiscal year working alongside Bill."