Robert Soucy, a stock picker at Grantham, Mayo, Van Otterloo & Co. LLC who helps manage two Vanguard Group mutual funds, will retire at year-end, the fund company said on Wednesday.

Soucy will be replaced on the $10.5 billion Vanguard Explorer Fund (VEXPX) and the $987 million Vanguard U.S. Value Fund (VUVLX) by Grantham, Mayo portfolio manager Sam Wilderman, starting in January.

Grantham, Mayo, known as GMO, has managed the U.S. Value Fund since its inception in June 2000, and oversees about 28% of the assets of the Explorer Fund, which is also managed by Vanguard and four other investment firms. Soucy had been part of Explorer’s management team since 2000.

Wilderman also will continue as director of U.S. equity management for GMO. He and Soucy are currently are co-directors. Wilderman, who joined the firm in 1996, previously was responsible for research and portfolio management for three GMO funds that invest in emerging markets.

The U.S. Value Fund returned 13.7% for the one-year period through September, versus a 13.6% gain by its large-cap value fund peers. The Explorer Fund rose 21.1% during the same period, compared to a 19.1% climb by the average small-cap growth fund. Both funds are ranked 3 Stars by Standard & Poor’s.

Vanguard also announced that the American Stock Exchange has begun trading options on two of the fund company’s exchange-traded funds that invest overseas, Vanguard European VIPERS (VGK), and Vanguard Pacific VIPERS (VPL).

Contact Bob Keane with questions or comments at: bkeane@investmentadvisor.com.