Set to be situated in Chicago, McCartney’s responsibilities will straddle both the firm’s US and international operations.
A member of the group since February 2020, McCartney has since served as vice president of ceded reinsurance for the Americas.
Before joining Argo, he was positioned in the same role for the allied world in Bermuda for the six years leading to 2018.
Tim Carter, executive vice president and chief underwriting officer, said: “Tom has been closely involved in shaping Argo’s reinsurance strategy.
“His strong technical skills and relationships in the market make him ideally suited for this important role. We look forward to working with Tom as we look to build on our past success.”
McCartney will be replacing the outgoing Katie Partington Howarth, who had held the role since June 2018.
Carter recognised the “contributions” made by Howarth during her time at the group, adding that the company wishes her “the best in the future”.