Investment objective & strategy
As of Oct. 27, 2025 · prospectusObjective. Fidelity Flex U.S. Bond Index Fund 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.
Strategy. Normally investing at least 80% of assets in bonds included in the Bloomberg U.S. Aggregate Bond Index. The Bloomberg U.S. Aggregate Bond Index is a broad based, flagship benchmark that measures the investment grade, US dollar-denominated, fixed-rate taxable bond market. The index includes Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate pass-throughs), asset-backed securities and collateralized mortgage-backed securities (agency and non-agency). Effective December 11, 2025, derivative instruments that provide investment exposure to the investments above or exposure to one or more market risk factors associated with such investments are included in the fund's 80% policy, consistent with the fund's investment policies and limitations with respect to investments in derivatives. Using statistical sampling techniques based on duration, maturity, interest rate … Normally investing at least 80% of assets in bonds included in the Bloomberg U.S. Aggregate Bond Index. The Bloomberg U.S. Aggregate Bond Index is a broad based, flagship benchmark that measures the investment grade, US dollar-denominated, fixed-rate taxable bond market. The index includes Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate pass-throughs), asset-backed securities and collateralized mortgage-backed securities (agency and non-agency). Effective December 11, 2025, derivative instruments that provide investment exposure to the investments above or exposure to one or more market risk factors associated with such investments are included in the fund's 80% policy, consistent with the fund's investment policies and limitations with respect to investments in derivatives. Using 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. Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure. Investing in Fidelity's Central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines) consistent with the asset classes discussed above.
Top holdings
As of Feb. 28, 2026 · N-PORT| Security | Ticker | Value | % of fund |
|---|---|---|---|
| US TREASURY N/B | — | $46.60M | 1.23% |
| Fidelity Cash Central Fund | — | $39.53M | 1.05% |
| US TREASURY N/B | — | $38.96M | 1.03% |
| US TREASURY N/B | — | $35.83M | 0.95% |
| US TREASURY N/B | — | $34.88M | 0.92% |
| US TREASURY N/B | — | $33.22M | 0.88% |
| US TREASURY N/B | — | $32.67M | 0.87% |
| US TREASURY N/B | — | $28.57M | 0.76% |
| US TREASURY N/B | — | $28.08M | 0.74% |
| US TREASURY N/B | — | $26.32M | 0.70% |
Portfolio moves
Nov 30, 2025 → Feb 28, 2026How many positions this fund opened, exited, grew, trimmed, or left unchanged between its two most recent N-PORT snapshots — net changes between point-in-time reports, not a trade log.
Similar funds
Funds whose portfolios most overlap this one, by weight| Fund | Overlap | Net exp. |
|---|---|---|
| Fidelity Series Bond Index Fund · FIFZX | 59% | 0.00% |
| Fidelity Sustainability Bond Index Fund · FNDSX | 59% | 0.10% |
| VIP Bond Index Portfolio | 54% | 0.14% |
Advisers
| Firm | Role |
|---|---|
| FMR Investment Management (UK) Limited | Sub-adviser |
| Fidelity Management & Research (Japan) Limited | Sub-adviser |
| Fidelity Management & Research (Hong Kong) Limited | Sub-adviser |
| Fidelity Management & Research Company LLC | Adviser |
Footnotes
- Expense ratio as of October 27, 2025, from the fund's prospectus.
- Net assets and holdings count as of February 28, 2026, from the fund's N-PORT filing.
- Total return for calendar year 2025, before tax and after fund expenses. Computed by compounding the twelve monthly total returns the fund reported in its SEC N-PORT filings for 2025 (the latest prospectus does not yet chart this year).
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