Andrew Kirton, Mercer's global head of investment consulting, was named global chief investment officer.
The position is new, confirmed spokesman Charles Salmans.
Mr. Kirton will report to Phil de Cristo, president and group executive of investments.
Asghar Alam, who was U.S. regional business leader for retirement, risk and finance, was named global head of investment consulting, replacing Mr. Kirton.
Jacques Goulet, Mercer's Europe, Middle East and Africa head of retirement, risk and finance consulting, will succeed Mr. Alam. Gilles Beneplanc, EMEA region leader, will assume Mr. Goulet's responsibilities on an interim basis until a successor can be named.
Also, David Goldenberg, Mercer's general counsel, will move into the investment business as global head of solutions management, reporting to Mr. de Cristo. The position is new, Mr. Salmans said. A successor to the general counsel's position will be named at a later date, according to a news release.