The new appointments, William Freda and David Brown, will take on the roles of board chair and interim group CEO, respectively.
Duperreault, who left Hamilton Insurance this month, has joined AIG as CEO, director and president.
Freda joined the Hamilton board of directors in June 2014 and also chairs the board’s audit committee.
Brown has been a member of the board since Hamilton’s establishment in December 2013 and is chair of the finance and governance committee.
Freda commented: “It is with regret that we have accepted Brian Duperreault’s resignation from Hamilton. He is an industry icon with a well-deserved reputation for visionary leadership. We have had the privilege of experiencing this first-hand at Hamilton.”
He added: “However, we have in David Brown an experienced industry CEO who has been with the company since inception. He is an ideal resource to lead Hamilton through this transition.”