Frank Williamson, the chief investment officer at Unum Group Corp., is resigning from the position to pursue other interests, the company says.

Williamson has been in charge of investments at Unum, Chattanooga, Tenn. (NYSE:UNM), for 2 years, and he has worked for the company for 15 years.

He will stay with Unum temporarily in an advisory capacity, the company says.

David Fussell, who retired from the Unum chief investment officer post in February2008, will be the interim investment chief until a successor is named, the company says.

“Frank has made tremendous contributions to Unum over the last 15 years, and we certainly wish him well as he pursues other personal and professional interests,” Unum President Thomas Watjen says in a statement about Williamson’s’ resignation.