FundWatcher
MBB
iShares MBS ETF
iShares Trust
ETFIndex fund

Portfolio concentration

As of February 28, 2026 · N-PORT
Holdings
11151
Top-10 weight
11.23%
Effective holdings ?
230
Crowding ?
53.6

Holdings

As of February 28, 2026 · N-PORT
#SecurityTickerSharesValue% of fund
1 BlackRock Cash Funds: Treasury, SL Agency Shares — 2,348,574,595 $2.35B 5.90%
2 FR SD8146 — 511,173,406 $427.59M 1.07%
3 GNII II 5.5% 03/01/2056 #TBA — 394,483,000 $399.52M 1.00%
4 FNCL 5 3/24 — 226,772,000 $227.79M 0.57%
5 G2 MA7648 — 261,137,814 $221.29M 0.56%
6 G2 MA7766 — 256,664,507 $217.49M 0.55%
7 FN MA4492 — 255,146,804 $212.47M 0.53%
8 G2SF 5 3/25 — 209,187,000 $209.90M 0.53%
9 FR SD8140 — 244,776,593 $204.52M 0.51%
10 FNCL 5.5 3/25 — 194,629,000 $197.75M 0.50%
11 G2 MA7472 — 210,649,455 $185.94M 0.47%
12 Government National Mortgage Association, TBA GNR 177,486,000 $181.05M 0.45%
13 FN MA4465 — 216,504,308 $180.37M 0.45%
14 Uniform Mortgage-Backed Securities — 212,806,354 $178.33M 0.45%
15 G2 MB0025 — 167,611,848 $168.45M 0.42%
16 G2 MA7935 — 175,178,525 $148.44M 0.37%
17 G2 MA7367 — 163,884,478 $144.66M 0.36%
18 Uniform Mortgage-Backed Security, TBA FNCI 150,295,791 $140.02M 0.35%
19 FR SD8199 — 167,480,732 $139.53M 0.35%
20 FN MA4281 — 159,356,148 $133.21M 0.33%
21 Fannie Mae Pool — 159,358,647 $133.10M 0.33%
22 G2 MA9171 — 128,069,838 $130.72M 0.33%
23 FN MA4437 — 152,966,536 $127.60M 0.32%
24 G2 MA7826 — 148,373,643 $125.73M 0.32%
25 G2 MA7534 — 139,978,132 $123.56M 0.31%
26 FN MA4305 — 144,287,885 $120.56M 0.30%
27 Fannie Mae Pool — 138,247,370 $115.62M 0.29%
28 G2 MA7936 — 130,866,463 $115.52M 0.29%
29 G2 MA7051 — 134,569,387 $114.06M 0.29%
30 G2 MA7767 — 127,322,761 $112.39M 0.28%
31 G2 MA9965 — 107,349,977 $109.08M 0.27%
32 FR SD8324 — 101,057,674 $102.91M 0.26%
33 FNCL 6 3/24 — 98,775,000 $101.31M 0.25%
34 G2 MB0624 — 98,627,489 $100.71M 0.25%
35 FR SD8182 — 116,417,593 $96.95M 0.24%
36 FANNIE MAE POOL FN 05/52 FIXED VAR FN 101,344,892 $93.08M 0.23%
37 G2 MA9781 — 89,335,473 $93.02M 0.23%
38 G2 MA7987 — 105,087,174 $92.76M 0.23%
39 G2 MA7589 — 103,620,927 $91.47M 0.23%
40 FR SD8134 — 108,497,448 $90.69M 0.23%
41 FR SD8362 — 88,727,120 $90.32M 0.23%
42 Uniform Mortgage-Backed Securities FNMA 105,259,671 $87.66M 0.22%
43 Uniform Mortgage-Backed Securities — 84,644,496 $87.11M 0.22%
44 FR RA5205 — 99,444,364 $87.09M 0.22%
45 FNCL UMBS 3.0 CA9308 02-01-51 — 94,457,157 $85.65M 0.22%
46 G2 MA9852 — 82,818,664 $84.80M 0.21%
47 Uniform Mortgage-Backed Securities — 80,606,374 $82.18M 0.21%
48 G2 MB0091 — 80,229,360 $80.61M 0.20%
49 Freddie Mac Pool — 78,678,814 $79.80M 0.20%
50 FR SD8234 — 89,333,741 $77.79M 0.20%
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