# Portfolio overlap — FIBUX vs FIFZX

Comparing **Fidelity Flex U.S. Bond Index Fund** (2026-02-28) and **Fidelity Series Bond Index Fund** (2026-02-28).

- Shared positions: 3642
- Fidelity Flex U.S. Bond Index Fund covered by Fidelity Series Bond Index Fund: 0.5949012549176373357193871549
- Fidelity Series Bond Index Fund covered by Fidelity Flex U.S. Bond Index Fund: 0.5949012549176373357193871548

## Fidelity Flex U.S. Bond Index Fund — top positions

| Security | Weight | Shared |
|----------|--------|--------|
| US TREASURY N/B | 0.011961 |  |
| Fidelity Cash Central Fund | 0.010147 | ✓ |
| US TREASURY N/B | 0.010000 | ✓ |
| US TREASURY N/B | 0.009197 | ✓ |
| US TREASURY N/B | 0.008954 | ✓ |
| US TREASURY N/B | 0.008527 | ✓ |
| US TREASURY N/B | 0.008386 | ✓ |
| US TREASURY N/B | 0.007334 | ✓ |
| US TREASURY N/B | 0.007207 | ✓ |
| US TREASURY N/B | 0.006755 | ✓ |
| US TREASURY N/B | 0.006648 | ✓ |
| US TREASURY N/B | 0.006446 | ✓ |
| US TREASURY N/B | 0.006216 | ✓ |
| US TREASURY N/B | 0.006145 | ✓ |
| US TREASURY N/B | 0.006069 | ✓ |
| US TREASURY N/B | 0.005936 | ✓ |
| US TREASURY N/B | 0.005779 | ✓ |
| US TREASURY N/B | 0.005660 | ✓ |
| US TREASURY N/B | 0.005528 | ✓ |
| US TREASURY N/B | 0.005519 | ✓ |
| US TREASURY N/B | 0.004975 | ✓ |
| US TREASURY N/B | 0.004969 | ✓ |
| US TREASURY N/B | 0.004874 | ✓ |
| US TREASURY N/B | 0.004847 | ✓ |
| US TREASURY N/B | 0.004841 | ✓ |
| US TREASURY N/B | 0.004798 | ✓ |
| US TREASURY N/B | 0.004758 | ✓ |
| US TREASURY N/B | 0.004677 | ✓ |
| US TREASURY N/B | 0.004596 | ✓ |
| US TREASURY N/B | 0.004498 | ✓ |
| US TREASURY N/B | 0.004324 | ✓ |
| US TREASURY N/B | 0.004317 | ✓ |
| US TREASURY N/B | 0.004317 | ✓ |
| US TREASURY N/B | 0.004180 | ✓ |
| US TREASURY N/B | 0.004008 | ✓ |
| US TREASURY N/B | 0.003974 | ✓ |
| US TREASURY N/B | 0.003938 | ✓ |
| US TREASURY N/B | 0.003861 | ✓ |
| US TREASURY N/B | 0.003768 | ✓ |
| US TREASURY N/B | 0.003642 | ✓ |
| US TREASURY N/B | 0.003520 | ✓ |
| US TREASURY N/B | 0.003485 | ✓ |
| US TREASURY N/B | 0.003404 | ✓ |
| US TREASURY N/B | 0.003355 | ✓ |
| G2SF 5 3/25 | 0.003342 | ✓ |
| US TREASURY N/B | 0.003233 | ✓ |
| US TREASURY N/B | 0.003213 | ✓ |
| US TREASURY N/B | 0.003097 | ✓ |
| GNII II 5.5% 03/01/2056 #TBA | 0.003074 | ✓ |
| US TREASURY N/B | 0.003038 | ✓ |

## Fidelity Series Bond Index Fund — top positions

| Security | Weight | Shared |
|----------|--------|--------|
| US TREASURY N/B | 0.011257 | ✓ |
| US TREASURY N/B | 0.010648 | ✓ |
| US TREASURY N/B | 0.009228 | ✓ |
| US TREASURY N/B | 0.008011 | ✓ |
| US TREASURY N/B | 0.007152 | ✓ |
| US TREASURY N/B | 0.006840 | ✓ |
| US TREASURY N/B | 0.006594 | ✓ |
| Fidelity Cash Central Fund | 0.006318 | ✓ |
| US TREASURY N/B | 0.006218 | ✓ |
| US TREASURY N/B | 0.006205 | ✓ |
| US TREASURY N/B | 0.006178 | ✓ |
| Fidelity Securities Lending Cash Central Fund | 0.005920 |  |
| US TREASURY N/B | 0.005903 | ✓ |
| US TREASURY N/B | 0.005772 | ✓ |
| US TREASURY N/B | 0.005443 | ✓ |
| US TREASURY N/B | 0.005260 | ✓ |
| US TREASURY N/B | 0.005202 | ✓ |
| US TREASURY N/B | 0.004961 | ✓ |
| US TREASURY N/B | 0.004954 | ✓ |
| US TREASURY N/B | 0.004949 | ✓ |
| US TREASURY N/B | 0.004926 | ✓ |
| FR SD8121 | 0.004907 | ✓ |
| US TREASURY N/B | 0.004843 | ✓ |
| US TREASURY N/B | 0.004554 | ✓ |
| US TREASURY N/B | 0.004535 | ✓ |
| US TREASURY N/B | 0.004417 | ✓ |
| US TREASURY N/B | 0.004405 | ✓ |
| US TREASURY N/B | 0.004379 | ✓ |
| US TREASURY N/B | 0.004205 | ✓ |
| US TREASURY N/B | 0.004121 | ✓ |
| US TREASURY N/B | 0.003897 | ✓ |
| US TREASURY N/B | 0.003895 | ✓ |
| US TREASURY N/B | 0.003890 | ✓ |
| US TREASURY N/B | 0.003882 | ✓ |
| US TREASURY N/B | 0.003846 | ✓ |
| US TREASURY N/B | 0.003830 | ✓ |
| US TREASURY N/B | 0.003818 | ✓ |
| US TREASURY N/B | 0.003748 | ✓ |
| US TREASURY N/B | 0.003696 | ✓ |
| US TREASURY N/B | 0.003667 | ✓ |
| US TREASURY N/B | 0.003631 |  |
| US TREASURY N/B | 0.003625 | ✓ |
| US TREASURY N/B | 0.003611 | ✓ |
| US TREASURY N/B | 0.003608 | ✓ |
| US TREASURY N/B | 0.003580 | ✓ |
| US TREASURY N/B | 0.003496 |  |
| US TREASURY N/B | 0.003480 | ✓ |
| US TREASURY N/B | 0.003479 | ✓ |
| G2SF 5 3/25 | 0.003405 | ✓ |
| US TREASURY N/B | 0.003367 | ✓ |


## Sources

- N-PORT (fund A) — accession `0000035402-26-002575` (as of 2026-02-28)
  <https://www.sec.gov/Archives/edgar/data/35315/000003540226002575/0000035402-26-002575-index.htm>
- N-PORT (fund B) — accession `0000035402-26-002627` (as of 2026-02-28)
  <https://www.sec.gov/Archives/edgar/data/35315/000003540226002627/0000035402-26-002627-index.htm>

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_Data sourced from U.S. SEC EDGAR filings (Forms N-PORT, N-CEN, and prospectus Risk/Return summaries). FundWatcher is not affiliated with the SEC._

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