Vanguard Group

plans to beef up management of the $16.5 billion

(VWNDX) - Get Report

Windsor fund and reopen it to new investors on June 1. The 41-year-old fund has been closed since 1989.

Once a popular market beater, Windsor returned just 0.8% last year, lagging far behind the

S&P 500's

return of 28.6%.

The Malvern, Pa., fund group says it will switch to a multiadviser approach for Windsor, which has been managed by Charles Freeman at

Wellington Asset Management

since 1996.

While Freeman and Wellington will continue to be the lead adviser for the fund, some of the fund's assets will now be handled by

Sanford C. Bernstein

. The New York-based value investment firm currently oversees $80 billion in assets. Marilyn G. Fedak, chief investment officer for U.S. equity, and Steven Pisarkiewicz, senior portfolio manager, will serve as co-managers for Bernstein.

"Our confidence in portfolio manager Charles T. Freeman and his team at Wellington Management Company remains firm," says Vanguard Chairman and Chief Executive John J. Brennan in a press release. "We are convinced that this structure -- bringing together the talents of two renowned value teams -- serves the best interests of Windsor's shareholders," he says.

When the fund reopens in June, it will be available to new investors with a minimum initial investment of $3,000.