George U. "Gus" Sauter, managing director and chief investment officer of Vanguard, a leading investment management company with $2.1 trillion in global assets, will step down as of Dec. 31. He will be succeeded by Managing Director Mortimer J. "Tim" Buckley.

Sauter, 57, has been with Vanguard since 1987 and currently directs Vanguard's global investment management groups, which oversee aggregate assets of $1.6 trillion. During his career, he oversaw the expansion of Vanguard's index line-up, which now has $1.1 trillion in aggregate index assets.

He also was responsible for developing Vanguard's active quantitative equity strategies, which now has 15 domestic active mandates totaling $12.1 billion under the Vanguard Equity Income Group.

Sauter led Vanguard's foray into exchange-traded funds by developing a structure under which ETFs are offered as a separate share class of existing Vanguard index funds. The company's first ETF, Vanguard Total Stock Market ETF, is now one of the largest in the industry with $20 billion in aggregate assets. Vanguard, based in Valley Forge, Pa., now offers 64 ETFs with nearly $200 billion in aggregate assets.

In 2003, Sauter was named Vanguard's fist CIO. Recently, he has focused on integrating Vanguard's global investment management capabilities to support the company's global expansion.

"I look back with a mixture of pride and humility on helping to popularize the indexing concept. I am also grateful for being associated with Vanguard for nearly my entire career, for it's an organization that truly stands alone in putting the interests of its clients first," said Sauter, who is considering teaching and other options after retirement.

Sauter's successor, Buckley, 43, joined Vanguard in 1991 and has been a member of Vanguard's senior staff since 2001. He has directed Vanguard's Retail Investor Group since 2006. The group serves 5,000,000 individual investors through its client services, high-net-worth, brokerage, advice, annuity, college savings and processing operations.

Buckley also is a member of Vanguard's Portfolio Review Group, which is responsible for overseeing Vanguard's in-house investment management functions and 30 external investment advisory firms employed by Vanguard.

-Karen DeMasters