UnitedHealth said on Thursday it will replace its finance chief John Rex with an external hire, Wayne DeVeydt, adding to the management changes at the health insurer that has been struggling to control its medical costs.

Wayne DeVeydt, a healthcare veteran who most recently worked at Bain Capital, will take up the finance chief job on Sept. 2 as the healthcare behemoth faces an array of operational challenges.

After a year that has seen its share price collapse by more than 50%, UnitedHealth Group (UNH) has swapped out its chief financial officer. Wayne DeVeydt will take over as CFO of UnitedHealth effective Sept.