Stephens Investment Management Group LLC has been added as an advisor to the $11.4 billion Vanguard Explorer Fund, Vanguard announced Monday. 

This is the first Vanguard advisory mandate for Stephens, a Little Rock, Ark., and Houston-based investment advisory firm with more than $1.5 billion under management. Ryan Crane, chief investment officer of Stephens, serves as portfolio manager.

The Explorer Fund, a small-cap growth stock mutual fund, has employed a multi-manager structure since 1990 and now utilizes seven advisors.