Lehman Aggregate Bond Index: An index used by bond funds as a benchmark to measure their relative performance. The index includes government securities, mortgage-backed securities , asset-backed l ®Fidelity U.S. Bond Index Fund is a diversified fixed-income strategy that seeks to closely track the returns and characteristics of the benchmark Bloomberg Barclays U.S. Aggregate Bond Index. l Given the large number of securities in the index (roughly 10,000) and the significant cost and liquidity Barclays Aggregate Bond Index Portfolio (formerly, Barclays Capital Aggregate Bond Index Portfolio) Class A, Class B, Class E and Class G Shares . Before you invest, you may want to review the Portfolio’s Prospectus, which contains more information about the Portfolio and its risks.