The investment seeks to provide investment results that correspond to the aggregate price and interest performance of the debt securities in the Bloomberg U.S. Aggregate Bond Index. The fund normally invests at least 80% of its assets in bonds included in the Bloomberg U.S. Aggregate Bond Index. The advisor uses statistical sampling techniques based on duration, maturity, interest rate sensitivity, security structure, and credit quality to attempt to replicate the returns of the Bloomberg U.S. Aggregate Bond Index using a smaller number of securities. The fund invests in Fidelity's central funds.