Fidelity Series Bond Index Fund
U.S. bond index fund · tracks Bloomberg U.S. Aggregate Bond Index
As of its 2026 Q2 report, Fidelity Series Bond Index Fund held 10,036 positions with $34.05B in net assets. Its ten largest holdings made up 9.3% of the fund. The FIFZX share class costs 0% a year. Over the 12 months to May 2026, FIFZX returned 5.2%, with dividends reinvested. In 2026 Q2 it added 396 new positions and exited 201.
Fidelity Series 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.
The fund tracks the Bloomberg U.S. Aggregate Bond Index using statistical sampling techniques, holding a representative subset of the index's Treasury, government, corporate, mortgage-backed, asset-backed, and collateralized mortgage-backed securities rather than all constituents. Because the fund samples the index based on duration, maturity, interest rate sensitivity, security structure, and credit quality, its returns may diverge from the index. The fund may use derivatives including swaps, options, and futures contracts to adjust its risk exposure.
What you own
| Company | Weight | Value | Shares |
|---|---|---|---|
UST NOTES 3.88% · due 2029-04-15 | 1.16% | $394.01M | — |
UST NOTES 3.75% · due 2028-05-15 | 1.12% | $381.11M | — |
UST NOTES 4.63% · due 2027-06-15 | 1.10% | $376.38M | — |
UST NOTES 4.13% · due 2036-02-15 | 1.09% | $372.30M | — |
UST NOTES 3.50% · due 2029-01-15 | 1.05% | $358.90M | — |
UNITED STATES TREASURY BOND 4.50% · due 2044-02-15 | 0.88% | $300.77M | — |
UST NOTES 3.88% · due 2028-06-15 | 0.80% | $270.87M | — |
UST NOTES 4.13% · due 2033-04-30 | 0.73% | $248.35M | — |
UNITED STATES TREASURY BOND 4.63% · due 2046-02-15 | 0.73% | $247.20M | — |
UNITED STATES TREASURY BOND 5.00% · due 2045-05-15 | 0.68% | $232.81M | — |
The 200 largest of 10,036 holdings, with the share counts as filed, open with a free account.
What the fund is made of
Percentages are of fund net assets. Rounding, liabilities and short positions can make totals differ from 100%.
| Bonds | 75.33% |
| Securitized | 25.11% |
| Cash & short-term | 0.76% |
By sector
- Government
- 46.9%
- Securitized
- 25.3%
- Financials
- 5.7%
- Other
- 4.6%
- 12 other sectors
- 17.5%
- Government
- 46.9%
- Securitized
- 25.3%
- Financials
- 5.7%
- Other
- 4.6%
- International
- 3.0%
- Utilities
- 2.6%
- Health Care
- 2.1%
- Communication Services
- 1.8%
- Information Technology
- 1.8%
- Industrials
- 1.6%
- Consumer Staples
- 1.1%
- Energy
- 0.9%
- Consumer Discretionary
- 0.8%
- Cash
- 0.7%
- Real Estate
- 0.7%
- Materials
- 0.4%
How it has done
FIFZX share class · total returns with dividends reinvested
Volatility over the last 12 months: 3.22%. Past returns are a record, not a forecast.
Fees & fund details
Fidelity Series Bond Index Fund is a U.S. bond index fund that tracks the Bloomberg U.S. Aggregate Bond Index.
- Asset class
- Bonds
- Region
- United States
- Management
- Index (passive)
- Fund type
- Open-end fund
- Credit quality
- Investment grade
- Rate sensitivity
- Intermediate duration
- Expense ratio, by class
- 0.00%· FIFZX 0.00%
- Portfolio turnover
- 55.00% a year · as of 2025 Q4
Turnover is how much of the portfolio was replaced in a year.
Classified from what the fund holds, not from its name · 2026 Q2. The summary is a paraphrase of the prospectus; the objective is verbatim.
What changed this quarter
Positions that entered or left the fund since its previous filing. Positions that were only resized are not listed.
396 new· the largest 2
201 exited· the largest 2
Debt profile
What this fund holds — value-weighted across its bond and securitized long positions · as of 2026-05-31
Share of the fund's debt by how its coupon behaves — the fact that decides whether a rate move reaches this portfolio at all.
| Fixed rate | 95.0% |
| Floating rate | 5.0% |
Share of the fund's debt value in each maturity band, shortest first.
| <1y | 3.0% |
| 1-3y | 21.4% |
| 3-5y | 15.2% |
| 5-10y | 18.4% |
| 10y+ | 42.0% |
Based on what filers reported; a filer that never reported a flag also reads as none.
Risk profile
Interest-rate and credit-spread sensitivity, both in years · as of 2026Q2
More of this fund’s sensitivity sits in credit spreads than in interest rates — a rate rally that comes with a credit selloff works against it.
Where the loss would come from. The two shocks are the same size, so this is the balance of the fund's two sensitivities rather than a bet on one moving more.
| Credit spreads | 50% |
| Interest rates | 50% |
Filers report the impact of a 0.01% move only, so the total is our own scaling of that one number and overstates the loss on most bonds — read it as approximate, never as precise. The two sensitivities overlap rather than add up: they measure the same positions against different shocks, which is why the durations above are shown side by side and never summed.
Share of the fund's spread duration carried by each credit tier.
| Investment grade | +5.90 yr |
Share of duration at each point, shortest first. A positive figure loses value when spreads widen; a negative one offsets — a credit hedge.
| 3 mo | 0.01 yr | 0% |
| 1 yr | 0.54 yr | 9% |
| 5 yr | 1.44 yr | 25% |
| 10 yr | 2.05 yr | 35% |
| 30 yr | 1.77 yr | 30% |
| 3 mo | 0.14 yr | 2% |
| 1 yr | 0.93 yr | 16% |
| 5 yr | 1.86 yr | 32% |
| 10 yr | 2.05 yr | 35% |
| 30 yr | 0.93 yr | 16% |
The two bands measure the same positions against different shocks and do not add — a Treasury carries rate duration and no spread duration, a floating-rate credit the reverse. Rate tenors are also summed across every currency the fund discloses.
Show the numbers
| Tenor | Rate yrs | IG yrs | HY yrs | IG $/bp | HY $/bp |
|---|---|---|---|---|---|
| 3 mo | +0.01 | +0.14 | +0.00 | $484.2k | $0 |
| 1 yr | +0.54 | +0.93 | +0.00 | $3.15m | $0 |
| 5 yr | +1.44 | +1.86 | +0.00 | $6.33m | $0 |
| 10 yr | +2.05 | +2.05 | +0.00 | $6.97m | $0 |
| 30 yr | +1.77 | +0.93 | +0.00 | $3.15m | $0 |
Dollar change per 1bp of spread movement, as filed and sign-anchored. A blank cell was not filed; a zero was.
Understand how this fund fits with the rest.
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