# Portfolio overlap — FIBUX vs IUSB

Comparing **Fidelity Flex U.S. Bond Index Fund** (2026-02-28) and **iShares Core Universal USD Bond ETF** (2026-01-31).

- Shared positions: 3965
- Fidelity Flex U.S. Bond Index Fund covered by iShares Core Universal USD Bond ETF: 0.3389961466624833606298580311
- iShares Core Universal USD Bond ETF covered by Fidelity Flex U.S. Bond Index Fund: 0.3389961466624833606298580307

## 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 | ✓ |

## iShares Core Universal USD Bond ETF — top positions

| Security | Weight | Shared |
|----------|--------|--------|
| Blackrock Liquidity TempCash Inst | 0.023010 |  |
| BlackRock Cash Funds: Treasury, SL Agency Shares | 0.007770 |  |
| US TREASURY N/B | 0.003831 | ✓ |
| US TREASURY N/B | 0.003785 | ✓ |
| US TREASURY N/B | 0.003777 |  |
| US TREASURY N/B | 0.003775 |  |
| US TREASURY N/B | 0.003711 | ✓ |
| US TREASURY N/B | 0.003708 | ✓ |
| US TREASURY N/B | 0.003548 | ✓ |
| US TREASURY N/B | 0.003495 | ✓ |
| US TREASURY N/B | 0.003432 |  |
| US TREASURY N/B | 0.003366 | ✓ |
| FN MA4018 | 0.003335 |  |
| US TREASURY N/B | 0.003275 | ✓ |
| US TREASURY N/B | 0.003210 |  |
| US TREASURY N/B | 0.003197 |  |
| US TREASURY N/B | 0.003052 | ✓ |
| US TREASURY N/B | 0.002966 | ✓ |
| US TREASURY N/B | 0.002932 | ✓ |
| US TREASURY N/B | 0.002756 | ✓ |
| US TREASURY N/B | 0.002756 | ✓ |
| US TREASURY N/B | 0.002717 | ✓ |
| US TREASURY N/B | 0.002668 | ✓ |
| US TREASURY N/B | 0.002655 | ✓ |
| US TREASURY N/B | 0.002640 | ✓ |
| US TREASURY N/B | 0.002620 |  |
| US TREASURY N/B | 0.002614 | ✓ |
| US TREASURY N/B | 0.002590 |  |
| US TREASURY N/B | 0.002588 |  |
| US TREASURY N/B | 0.002547 | ✓ |
| US TREASURY N/B | 0.002547 | ✓ |
| US TREASURY N/B | 0.002473 | ✓ |
| US TREASURY N/B | 0.002452 |  |
| US TREASURY N/B | 0.002428 | ✓ |
| US TREASURY N/B | 0.002422 | ✓ |
| US TREASURY N/B | 0.002419 |  |
| US TREASURY N/B | 0.002404 | ✓ |
| US TREASURY N/B | 0.002394 |  |
| US TREASURY N/B | 0.002390 | ✓ |
| US TREASURY N/B | 0.002343 | ✓ |
| US TREASURY N/B | 0.002333 | ✓ |
| US TREASURY N/B | 0.002294 | ✓ |
| US TREASURY N/B | 0.002260 | ✓ |
| US TREASURY N/B | 0.002248 | ✓ |
| US TREASURY N/B | 0.002241 | ✓ |
| US TREASURY N/B | 0.002226 | ✓ |
| US TREASURY N/B | 0.002211 |  |
| G2 MA7192 | 0.002184 | ✓ |
| US TREASURY N/B | 0.002144 | ✓ |
| US TREASURY N/B | 0.002127 | ✓ |


## 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 `0002071691-26-007327` (as of 2026-01-31)
  <https://www.sec.gov/Archives/edgar/data/1100663/000207169126007327/0002071691-26-007327-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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