# Portfolio overlap — VMBS vs FIFZX

Comparing **VANGUARD MORTGAGE-BACKED SECURITIES INDEX FUND** (2026-02-28) and **Fidelity Series Bond Index Fund** (2026-02-28).

- Shared positions: 970
- VANGUARD MORTGAGE-BACKED SECURITIES INDEX FUND covered by Fidelity Series Bond Index Fund: 0.09225640180660313505227794766
- Fidelity Series Bond Index Fund covered by VANGUARD MORTGAGE-BACKED SECURITIES INDEX FUND: 0.09225640180660313505227794764

## VANGUARD MORTGAGE-BACKED SECURITIES INDEX FUND — top positions

| Security | Weight | Shared |
|----------|--------|--------|
| Vanguard Market Liquidity Fund | 0.044282 |  |
| G2SF 5 3/25 | 0.004266 | ✓ |
| Uniform Mortgage-Backed Security, TBA | 0.004210 | ✓ |
| Uniform Mortgage-Backed Security, TBA | 0.003278 |  |
| FNCL 5 3/24 | 0.003069 | ✓ |
| G2 MB0936 | 0.002821 |  |
| FR SD4155 | 0.002804 |  |
| G2 MB0025 | 0.002669 | ✓ |
| FR SD8146 | 0.002634 | ✓ |
| FNCL 5.5 3/25 | 0.002488 |  |
| FR SD8128 | 0.002380 | ✓ |
| FN MA4325 | 0.002360 | ✓ |
| G2 MA8347 | 0.002253 | ✓ |
| G2 MA7311 | 0.002190 | ✓ |
| G2 MB0624 | 0.002170 | ✓ |
| FR SD8106 | 0.002146 | ✓ |
| Uniform Mortgage-Backed Security, TBA | 0.002096 | ✓ |
| G2 MA7135 | 0.002075 | ✓ |
| FR SD8134 | 0.002071 | ✓ |
| G2 MA7826 | 0.002014 | ✓ |
| FR SD8121 | 0.002011 | ✓ |
| G2 MA6994 | 0.002011 |  |
| FN FS1560 | 0.002010 |  |
| FR RQ0028 | 0.001924 |  |
| Uniform Mortgage-Backed Security, TBA | 0.001890 | ✓ |
| FN MA4378 | 0.001887 |  |
| FR SD8506 | 0.001884 |  |
| FN MA4305 | 0.001873 | ✓ |
| G2 MB0024 | 0.001868 | ✓ |
| G2 MA8267 | 0.001853 | ✓ |
| G2 MB0485 | 0.001824 |  |
| FR SD8177 | 0.001820 | ✓ |
| FR SD1507 | 0.001803 |  |
| FN MA4119 | 0.001795 | ✓ |
| FN MA4255 | 0.001752 | ✓ |
| FR SD8493 | 0.001748 | ✓ |
| G2 MA7471 | 0.001726 | ✓ |
| FR SD8182 | 0.001678 |  |
| G2 MB0091 | 0.001644 | ✓ |
| FN MA4600 | 0.001644 | ✓ |
| G2 MB0146 | 0.001644 | ✓ |
| FR SD8463 | 0.001625 | ✓ |
| G2 MA9605 | 0.001612 |  |
| FR SD8474 | 0.001594 | ✓ |
| FN FS5129 | 0.001566 |  |
| G2 MB0365 | 0.001564 |  |
| G2 MB0092 | 0.001559 |  |
| FR SD8155 | 0.001550 |  |
| FN MA5445 | 0.001544 | ✓ |
| FN MA4437 | 0.001540 | ✓ |

## 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 `0001021882-26-000290` (as of 2026-02-28)
  <https://www.sec.gov/Archives/edgar/data/1021882/000102188226000290/0001021882-26-000290-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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