The Vanguard Group Inc., a retirement plan provider and investment manager, says CEO F. William McNabb III will take on the role of board chairman in January.

McNabb, 52, succeeds John J. Brennan, who was CEO from 1996 to August 2008 when McNabb stepped into the role as part of a transition plan announced earlier that year. The change in chairman is also part of that plan, says spokeswoman Linda Wolohan.

Brennan, 55, has been chairman of the Valley Forge-based mutual funds company since January 1998.

His plans were uncertain and he'll likely continue to offer guidance to members of the management team, but is relinquishing his formal duties as chairman, Wolohan says.