# Portfolio overlap — MBB vs IUSB

Comparing **iShares MBS ETF** (2026-02-28) and **iShares Core Universal USD Bond ETF** (2026-01-31).

- Shared positions: 1191
- iShares MBS ETF covered by iShares Core Universal USD Bond ETF: 0.1145365836009398314913723428
- iShares Core Universal USD Bond ETF covered by iShares MBS ETF: 0.1145365836009398314913723419

## iShares MBS ETF — top positions

| Security | Weight | Shared |
|----------|--------|--------|
| BlackRock Cash Funds: Treasury, SL Agency Shares | 0.056553 | ✓ |
| FR SD8146 | 0.010291 | ✓ |
| GNII II 5.5% 03/01/2056 #TBA | 0.009615 |  |
| FNCL 5 3/24 | 0.005482 |  |
| G2 MA7648 | 0.005326 | ✓ |
| G2 MA7766 | 0.005234 | ✓ |
| FN MA4492 | 0.005114 | ✓ |
| G2SF 5 3/25 | 0.005052 |  |
| FR SD8140 | 0.004922 | ✓ |
| FNCL 5.5 3/25 | 0.004759 |  |
| G2 MA7472 | 0.004475 | ✓ |
| Government National Mortgage Association, TBA | 0.004357 | ✓ |
| FN MA4465 | 0.004341 | ✓ |
| Uniform Mortgage-Backed Securities | 0.004292 | ✓ |
| G2 MB0025 | 0.004054 | ✓ |
| G2 MA7935 | 0.003572 |  |
| G2 MA7367 | 0.003481 | ✓ |
| Uniform Mortgage-Backed Security, TBA | 0.003370 |  |
| FR SD8199 | 0.003358 | ✓ |
| FN MA4281 | 0.003206 | ✓ |
| Fannie Mae Pool | 0.003203 |  |
| G2 MA9171 | 0.003146 | ✓ |
| FN MA4437 | 0.003071 | ✓ |
| G2 MA7826 | 0.003026 | ✓ |
| G2 MA7534 | 0.002974 | ✓ |
| FN MA4305 | 0.002901 | ✓ |
| Fannie Mae Pool | 0.002783 |  |
| G2 MA7936 | 0.002780 | ✓ |
| G2 MA7051 | 0.002745 | ✓ |
| G2 MA7767 | 0.002705 | ✓ |
| G2 MA9965 | 0.002625 | ✓ |
| FR SD8324 | 0.002477 | ✓ |
| FNCL 6 3/24 | 0.002438 |  |
| G2 MB0624 | 0.002424 | ✓ |
| FR SD8182 | 0.002333 | ✓ |
| FANNIE MAE POOL FN 05/52 FIXED VAR | 0.002240 |  |
| G2 MA9781 | 0.002239 | ✓ |
| G2 MA7987 | 0.002232 | ✓ |
| G2 MA7589 | 0.002201 | ✓ |
| FR SD8134 | 0.002183 |  |
| FR SD8362 | 0.002174 | ✓ |
| Uniform Mortgage-Backed Securities | 0.002110 | ✓ |
| Uniform Mortgage-Backed Securities | 0.002096 | ✓ |
| FR RA5205 | 0.002096 |  |
| FNCL UMBS 3.0 CA9308 02-01-51 | 0.002061 |  |
| G2 MA9852 | 0.002041 | ✓ |
| Uniform Mortgage-Backed Securities | 0.001978 | ✓ |
| G2 MB0091 | 0.001940 | ✓ |
| Freddie Mac Pool | 0.001921 |  |
| FR SD8234 | 0.001872 |  |

## 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 `0001410368-26-039527` (as of 2026-02-28)
  <https://www.sec.gov/Archives/edgar/data/1100663/000141036826039527/0001410368-26-039527-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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