Vanguard Small-Cap Index Fund Institutional Shares 

This low-cost index fund provides broad exposure to the small-capitalization U.S. equity market. The fund seeks to track an index of small-sized companies. One of the fund’s primary risks is its focus on the small-cap arena, which is an often-volatile segment of the market. Investors looking to add a small-cap equity allocation to an already diversified portfolio may wish to consider this option.