Vanguard Group announced Thursday that F. William McNabb, the company’s president and chief executive officer, will succeed John J. Brennan as chairman of the $1.3 trillion investment management company effective Jan. 1.

McNabb, 52, has been chief executive since Aug. 31, 2008, a position he assumed from Brennan after a six-month transition plan. McNabb succeeding Brennan as chairman was part of that initial transition plan, according to John Woerth, a spokesman for Vanguard.

Brennan, 55, will no longer have executive responsibilities at Vanguard, but will still be involved in industry affairs. Woerth said the company expects he will continue to work with regulators and legislators on money market fund issues “and other issues of importance for fund investors.”

Brennan, who has worked for Vanguard since 1982, was its chief executive officer from January 1996 to August 2008 and chairman since January 1998.

McNabb has worked for Vanguard, which had $1.3 trillion in assets under management as of Sept. 30, in June 1986 and has held various senior leadership positions during his career, including directing Vanguard’s institutional and retail divisions. McNabb, who will continue as president and chief executive officer, becomes only the third chairman in Vanguard’s 34-year history, following Brennan and John Bogle.

McNabb took over as CEO at the height of the economic crisis. During an interview, two months afetr taking the helm, he called the environment "Vanguard weather," and helped the company add customers during the difficult period.  

“Bill has done an extraordinary job leading Vanguard during this tumultuous period, and the board of directors and I have full confidence in his ability to steer Vanguard’s future course,” Brennan said. Vanguard, which is based in Valley Forge, Pa., offers more than 160 funds to U.S. investors and more than 50 additional funds in non-U.S. markets.