The investment seeks to track the investment results (before fees and expenses) of the FTSE RAFI? US Mid Small 1500 Index. The fund generally will invest at least 90% of its total assets in the securities that comprise the underlying index. The underlying index is composed of 1,500 common stocks that the index provider strictly in accordance with its guidelines and mandated procedures, include to track the performance of small- and medium-sized U.S. companies based on the following four fundamental measures of firm size: book value, cash flow, sales and dividends.