Reddy has been serving as the company's CFO for Europe. Before that, he was at Mattel.
Vollero, who has been an executive at Mattel, is expected to become permanent CFO.
Fleming was CFO and executive vice president at Schottenstein Property Group.
Tait was CFO of Alterra Insurance U.S.
Joyner, a 19-year investment banker, is joining the company from Investec Bank.
Jackson has been named chief information officer. He was CFO at National Patient Account Services, a unit of HCA.