iShares MBS ETF (MBB) is an ETF managed by BlackRock / iShares. Its largest position is BLACKROCK CASH FUNDS TREASURY SL AGENCY SHARES (null), representing 5.90% of fund assets.
iShares MBS ETF Portfolio Holdings
Source: SEC Form N-PORT institutional portfolio disclosures
- Ticker:
- MBB
- Type:
- ETF
- Manager:
- BlackRock / iShares
- Total Assets:
- —
- Report Date:
- Feb 28, 2026
- Filing Date:
- Apr 23, 2026
| Holding | Weight | Market Value | Shares |
|---|---|---|---|
|
-
BLACKROCK CASH FUNDS TREASURY SL AGENCY SHARES
|
5.90% | $2,349,748,882.32 | 2,348,574,595 |
|
-
FEDERAL NATIONAL MORTGAGE ASSOCIATION
|
1.07% | $427,589,929.06 | 511,173,406 |
|
-
GOVERNMENT NATIONAL MORTGAGE ASSOCIATION
|
1.00% | $399,517,163.25 | 394,483,000 |
|
-
FANNIE MAE POOL MBS 30YR TBA
|
0.57% | $227,789,172.20 | 226,772,000 |
|
-
GNMA
|
0.56% | $221,285,634.59 | 261,137,814 |
|
-
GOVERNMENT NATIONAL MORTGAGE ASSOCIATION
|
0.55% | $217,494,998.47 | 256,664,507 |
|
-
FANNIE MAE
|
0.53% | $212,474,536.60 | 255,146,804 |
|
-
GOVERNMENT NATIONAL MORTGAGE ASSOCIATION
|
0.53% | $209,896,727.56 | 209,187,000 |
|
-
FHLMC POOL
|
0.51% | $204,523,050.63 | 244,776,593 |
|
-
FANNIE MAE POOL MBS 30YR TBA
|
0.50% | $197,749,445.88 | 194,629,000 |
|
-
GNMA
|
0.47% | $185,938,026.36 | 210,649,455 |
|
-
GINNIE MAE II POOL MBS 30YR TBA
|
0.45% | $181,046,291.07 | 177,486,000 |
|
-
FANNIE MAE
|
0.45% | $180,370,505.38 | 216,504,308 |
|
-
UMBS P#FS4654 2% 07/01/51
|
0.45% | $178,332,612.01 | 212,806,354 |
|
-
GOVERNMENT NATIONAL MORTGAGE ASSOCIATION
|
0.42% | $168,453,696.80 | 167,611,848 |
|
-
GOVERNMENT NATIONAL MORTGAGE ASSOCIATION
|
0.37% | $148,438,446.26 | 175,178,525 |
|
-
GOVERNMENT NATIONAL MORTGAGE A
|
0.36% | $144,659,079.64 | 163,884,478 |
|
-
FEDERAL NATIONAL MORTGAGE ASSOCIATION
|
0.35% | $140,022,705.46 | 150,295,791 |
|
-
FREDDIE MAC
|
0.35% | $139,528,303.51 | 167,480,732 |
|
-
FANNIE MAE
|
0.33% | $133,205,700.36 | 159,356,148 |
|
-
FANNIE MAE
|
0.33% | $133,096,404.12 | 159,358,647 |
|
-
GNMA
|
0.33% | $130,718,959.53 | 128,069,838 |
|
-
FEDERAL NATIONAL MORTGAGE ASSOCIATION
|
0.32% | $127,597,398.48 | 152,966,536 |
|
-
GOVERNMENT NATIONAL MORTGAGE ASSOCIATION
|
0.32% | $125,730,376.64 | 148,373,643 |
|
-
GOVERNMENT NATIONAL MORTGAGE ASSOCIATION
|
0.31% | $123,557,203.52 | 139,978,132 |
|
-
FANNIE MAE
|
0.30% | $120,559,723.67 | 144,287,885 |
|
-
FANNIE MAE
|
0.29% | $115,619,322.46 | 138,247,370 |
|
-
GOVERNMENT NATIONAL MORTGAGE ASSOCIATION
|
0.29% | $115,515,880.49 | 130,866,463 |
|
-
GNMA
|
0.29% | $114,056,581.14 | 134,569,387 |
|
-
GNMA
|
0.28% | $112,386,442.84 | 127,322,761 |
|
-
GNMA
|
0.27% | $109,076,526.13 | 107,349,977 |
|
-
FHLMC POOL
|
0.26% | $102,913,588.13 | 101,057,674 |
|
-
FEDERAL NATIONAL MORTGAGE ASSOCIATION
|
0.25% | $101,312,358.87 | 98,775,000 |
|
-
GOVERNMENT NATIONAL MORTGAGE ASSOCIATION
|
0.25% | $100,708,131.64 | 98,627,489 |
|
-
FHLMC POOL
|
0.24% | $96,947,222.98 | 116,417,593 |
|
-
FANNIE MAE
|
0.23% | $93,078,582.60 | 101,344,892 |
|
-
GOVERNMENT NATIONAL MORTGAGE ASSOCIATION
|
0.23% | $93,019,370.83 | 89,335,473 |
|
-
GOVERNMENT NATIONAL MORTGAGE ASSOCIATION
|
0.23% | $92,760,491.48 | 105,087,174 |
|
-
GOVERNMENT NATIONAL MORTGAGE ASSOCIATION
|
0.23% | $91,465,086.29 | 103,620,927 |
|
-
FREDDIE MAC
|
0.23% | $90,692,946.45 | 108,497,448 |
|
-
FREDDIE MAC
|
0.23% | $90,321,930.34 | 88,727,120 |
|
-
FANNIE MAE
|
0.22% | $87,655,418.50 | 105,259,671 |
|
-
FANNIE MAE
|
0.22% | $87,111,954.59 | 84,644,496 |
|
-
FREDDIE MAC
|
0.22% | $87,091,149.17 | 99,444,364 |
|
-
FANNIE MAE
|
0.22% | $85,646,847.71 | 94,457,157 |
|
-
GNMA
|
0.21% | $84,798,764.06 | 82,818,664 |
|
-
FANNIE MAE
|
0.21% | $82,184,209.52 | 80,606,374 |
|
-
GOVERNMENT NATIONAL MORTGAGE ASSOCIATION
|
0.20% | $80,607,537.41 | 80,229,360 |
|
-
FREDDIE MAC
|
0.20% | $79,799,967.76 | 78,678,814 |
|
-
FREDDIE MAC
|
0.20% | $77,789,632.23 | 89,333,741 |
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