Total Holdings
11,134
As of Apr 4, 2026
iShares MBS ETF
MBBNASDAQBlackRockFixed Income
$90.59Today:- (-)1Y −5.53%
As of Oct 15, 2026 close
- Assets (AUM)
- $37.10B
- Expense ratio
- 0.04%
- Dividend yield
- 4.49%
- Holdings
- 11,134
- 52-week range
- $88.58$96.97
- Volume (live)
- -
- Avg. volume (3M)
- 7.27M
MBB ETF Holdings: iShares MBS ETF
Every listed position with its portfolio weight, plus sector breakdown and geographic exposure for this Fixed Income ETF. Analyze fund diversification and concentration.
Top 10 Holdings
12.9%
Share of fund assets
Assets (AUM)
$37.10B
Total fund assets
Expense Ratio
0.04%
Annual management fee
Portfolio Allocations
Distribution breakdown by sector, asset type, and geographic region. Understand the fund's diversification strategy across markets and asset classes.
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Top 25 of 11,134 MBB Holdings by Portfolio Weight
Holdings as of Apr 4, 2026. Ticker, name, asset type and portfolio weight for each position. Fund disclosures available to us list the largest 25 positions.
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| # | Symbol | Name | Type | Weight |
|---|---|---|---|---|
| 1 | BISXX | BlackRock Cash Funds Instl SL Agency | Stock | 6.07% |
| 2 | G2SF.5.5 4.11 | Government National Mortgage Association 5.5% | Stock | 1.09% |
| 3 | FR.SD8146 | Federal Home Loan Mortgage Corp. 2% | Stock | 1.07% |
| 4 | FNCL.5 4.11 | Federal National Mortgage Association 5% | Stock | 1.07% |
| 5 | FNCL.5.5 4.11 | Federal National Mortgage Association 5.5% | Stock | 0.85% |
| 6 | G2.MB0025 | Government National Mortgage Association 5% | Stock | 0.57% |
| 7 | G2SF.5 4.11 | Government National Mortgage Association 5% | Stock | 0.57% |
| 8 | G2.MA7648 | Government National Mortgage Association 2% | Stock | 0.55% |
| 9 | G2.MA7766 | Government National Mortgage Association 2% | Stock | 0.54% |
| 10 | FN.MA4492 | Federal Home Loan Mortgage Corp. 2% | Stock | 0.53% |
| 11 | FR.SD8140 | Federal Home Loan Mortgage Corp. 2% | Stock | 0.51% |
| 12 | G2.MA7472 | Government National Mortgage Association 2.5% | Stock | 0.47% |
| 13 | G2SF.6 4.11 | Government National Mortgage Association 6% | Stock | 0.47% |
| 14 | FN.FS4654 | Federal National Mortgage Association 2% | Stock | 0.45% |
| 15 | FN.MA4465 | Federal Home Loan Mortgage Corp. 2% | Stock | 0.45% |
| 16 | FNCL.6 4.11 | Federal National Mortgage Association 6% | Stock | 0.44% |
| 17 | G2.MA7935 | Government National Mortgage Association 2% | Stock | 0.37% |
| 18 | G2.MA7367 | Government National Mortgage Association 2.5% | Stock | 0.36% |
| 19 | G2.MA9171 | Government National Mortgage Association 5.5% | Stock | 0.33% |
| 20 | FN.MA4281 | Federal Home Loan Mortgage Corp. 2% | Stock | 0.33% |
| 21 | FN.FS9130 | Federal National Mortgage Association 2% | Stock | 0.33% |
| 22 | FNCI.2 4.12 | Federal National Mortgage Association 2% | Stock | 0.33% |
| 23 | FN.MA4437 | Federal Home Loan Mortgage Corp. 2% | Stock | 0.32% |
| 24 | G2.MA9781 | Government National Mortgage Association 6.5% | Stock | 0.31% |
| 25 | G2.MA7826 | Government National Mortgage Association 2% | Stock | 0.31% |
Source: Fund holdings disclosures. Data as of Apr 4, 2026. Data sources and methodology
Frequently Asked Questions About iShares MBS ETF Holdings
What are the top holdings in MBB?
As of Apr 4, 2026, iShares MBS ETF (MBB) holds 11,134 securities. The largest are BlackRock Cash Funds Instl SL Agency (6.07%), Government National Mortgage Association 5.5% (1.09%), Federal Home Loan Mortgage Corp. 2% (1.07%). The holdings table lists each position by portfolio weight with its ticker, name and asset type.
How concentrated is MBB's portfolio?
As of Apr 4, 2026, the 10 largest positions make up 12.9% of MBB's assets. A concentrated portfolio has fewer large positions with higher individual weights, while a diversified portfolio distributes holdings more evenly.
What is MBB's sector allocation?
The Sector Allocation chart shows how MBB distributes investments across different industries like Technology, Healthcare, Financials, and more. This sector exposure helps understand the fund's industry diversification strategy.
What countries does MBB invest in?
MBB's geographic exposure is shown in the Countries tab under Portfolio Allocations. This reveals the fund's international diversification and exposure to different regions and global markets.
How diversified is MBB ETF?
MBB's diversification can be assessed by reviewing its 11,134 holdings (as of Apr 4, 2026), sector allocation, and geographic exposure. A well-diversified ETF spreads investments across multiple securities, sectors, and regions to reduce concentration risk.