Chubb Ltd., the insurer led by Chief Executive Officer Evan Greenberg, promoted Michael Kessler to chief reinsurance officer as William O’Farrell departs for other opportunities.

Kessler will oversee the design and purchase of the reinsurance programs and report to Chief Operating Officer John Keogh, the Zurich-based company said Thursday in a statement that didn’t specify where O’Farrell is headed. Kessler was previously chief actuary of Chubb’s international general-insurance business.

The insurer’s leadership has been shaken up over the past year after Greenberg’s firm, ACE Ltd., agreed to buy Chubb Corp. for more than $28 billion, helping it compete against rivals including American International Group Inc. and Berkshire Hathaway Inc. Chubb has promoted some executives as the companies integrate.

“Mike is an experienced actuarial executive with a long tenure at ACE and Chubb,” Keogh said in the statement. “He has impressive technical capabilities and experience, both U.S. and international actuarial experience, and deep first-hand insight into our businesses around the globe.”