Strategy. The Fund employs a passive management, or indexing, approach, which seeks to match approximately the performance of the Aggregate Bond Index before the deduction of Fund expenses. The Aggregate Bond Index represents a wide spectrum of public, investment grade, debt securities in the United States, including government, corporate, and international dollar-denominated bonds, as well as mortgage-backed securities (collectively, bonds). Some of these securities may be purchased with delayed delivery. Under normal circumstances, the Fund invests at least 80% of its net assets in a statistically selected sampling of bonds that are included in or correlated with the Aggregate Bond Index. The Fund does not necessarily invest in all of the bonds in the index, or in the same weightings. The … Show more… The Fund employs a passive management, or indexing, approach, which seeks to match approximately the performance of the Aggregate Bond Index before the deduction of Fund expenses. The Aggregate Bond Index represents a wide spectrum of public, investment grade, debt securities in the United States, including government, corporate, and international dollar-denominated bonds, as well as mortgage-backed securities (collectively, bonds). Some of these securities may be purchased with delayed delivery. Under normal circumstances, the Fund invests at least 80% of its net assets in a statistically selected sampling of bonds that are included in or correlated with the Aggregate Bond Index. The Fund does not necessarily invest in all of the bonds in the index, or in the same weightings. The Fund may invest in bonds not included in the Aggregate Bond Index which are selected to reflect characteristics such as maturity, duration, or credit quality similar to the Aggregate Bond Index. The Fund also may trade securities in segments of the portfolio to the extent necessary to closely mirror the duration of corresponding segments of the Index. As a result, the Fund may have different levels of interest rate, credit or prepayment risks from the levels of risks in the index. In addition, the Fund may have a higher portfolio turnover rate than that of other index funds. The Fund intends to be diversified in approximately the same proportion as the Aggregate Bond Index is diversified. The Fund may become nondiversified, as defined in the Investment Company Act of 1940 Act, as amended (the 1940 Act), solely as a result of a change in relative market capitalization or index weighting of one or more constituents of the Aggregate Bond Index. A nondiversified fund generally invests a greater proportion of its assets in the securities of one or more issuers and invests overall in a smaller number of issuers than a diversified fund. Shareholder approval will not be sought if the Fund becomes nondiversified due solely to a change in the relative market capitalization or index weighting of one or more constituents of the Aggregate Bond Index. Show less