MBB is a Bond ETF from iShares holding 11144 positions as of May 31, 2026, with $39.1B in assets and a 0.04% net expense ratio. Its largest positions are Freddie Mac Pool (1.0%), Ginnie Mae (0.9%) and Uniform Mortgage-Backed Security, TBA (0.8%); the top 10 holdings account for 6.8% of the portfolio. It yields 4.33% on a trailing-12-month basis.
- Issuer
- iShares
- Holdings
- 111446.8% cash, collateral & derivative positions excluded
- Net Assets
- $39.1BETF assets as of 2026-08-10
- Expense Ratio
- 0.04%per latest SEC prospectus filing
- TTM Yield
- 4.33%trailing 12-month distributions
Performance
- 1M
- -0.2%
- YTD
- +0.4%
- 1Y
- +3.9%
- 3Y (ann.)
- +4.7%
- 5Y (ann.)
- +0.3%
- 10Y (ann.)
- +1.2%
A $10,000 investment 10 years ago would be worth $11,289 today at the 10Y annualized rate. This is a backward-looking illustration, not a forecast. Project its future growth →
Total returns including dividends as of 2026-08-07. 3Y/5Y/10Y annualized. Past performance does not predict future results.
Top 25 Holdings
| # | Holding | Weight |
|---|---|---|
| 1 | Freddie Mac Pool | 1.05% |
| 2 | Ginnie Mae | 0.95% |
| 3 | Uniform Mortgage-Backed Security, TBA | 0.83% |
| 4 | Ginnie Mae | 0.67% |
| 5 | Uniform Mortgage-Backed Security, TBA | 0.64% |
| 6 | Ginnie Mae II Pool | 0.55% |
| 7 | Ginnie Mae II Pool | 0.54% |
| 8 | Ginnie Mae II Pool | 0.53% |
| 9 | Fannie Mae Pool | 0.52% |
| 10 | Freddie Mac Pool | 0.50% |
| 11 | Ginnie Mae | 0.46% |
| 12 | Ginnie Mae II Pool | 0.45% |
| 13 | Fannie Mae Pool | 0.44% |
| 14 | Fannie Mae Pool | 0.44% |
| 15 | Ginnie Mae II Pool | 0.41% |
| 16 | Ginnie Mae II Pool | 0.36% |
| 17 | Ginnie Mae II Pool | 0.35% |
| 18 | Uniform Mortgage-Backed Security, TBA | 0.34% |
| 19 | Fannie Mae Pool | 0.33% |
| 20 | Fannie Mae Pool | 0.33% |
| 21 | Fannie Mae Pool | 0.31% |
| 22 | Ginnie Mae II Pool | 0.31% |
| 23 | Ginnie Mae II Pool | 0.30% |
| 24 | Fannie Mae Pool | 0.30% |
| 25 | Ginnie Mae II Pool | 0.28% |
Showing the top 25 of 11144 holdings. See the full MBB holdings list →
MBB alternatives
The closest Bond ETFs to MBB by portfolio overlap — the share of weight both funds hold in the same securities.
| Fund | Overlap | Expense | Assets | |
|---|---|---|---|---|
 VMBSVanguard Mortgage-backed Securities Index Fund | 17% | 0.03%cheaper | $15.6B | Compare → |
 AGGiShares Core U.S. Aggregate Bond ETF | 17% | 0.03%cheaper | $137.7B | Compare → |
 EAGGiShares ESG Aware U.S. Aggregate Bond ETF | 13% | 0.1%pricier | $5.0B | Compare → |
 IUSBiShares Core Universal USD Bond ETF | 10% | 0.06%pricier | $43.2B | Compare → |
 SCHZSchwab U.S. Aggregate Bond ETF | 7% | 0.03%cheaper | $10.5B | Compare → |
 BNDVanguard Total Bond Market Index Fund | 5% | 0.03%cheaper | $161.4B | Compare → |
 BKAGBNY Mellon Core Bond ETF | 5% | 0%cheaper | $2.2B | Compare → |
| 5% | 0.36%pricier | $27.3B | Compare → |
Frequently Asked Questions
What is MBB's expense ratio?
MBB has a net expense ratio of 0.04%, per its latest SEC prospectus filing. That works out to about $4 a year on a $10,000 investment.
How many holdings does MBB have?
MBB held 11144 positions as of May 31, 2026, per its latest official holdings data. Cash, collateral and derivative positions (6.8% of portfolio weight) are excluded from that count.
What are MBB's top 10 holdings?
MBB's largest positions are Freddie Mac Pool (1.0%), Ginnie Mae (0.9%), Uniform Mortgage-Backed Security, TBA (0.8%), Ginnie Mae (0.7%), Uniform Mortgage-Backed Security, TBA (0.6%), Ginnie Mae II Pool (0.5%), Ginnie Mae II Pool (0.5%), Ginnie Mae II Pool (0.5%), Fannie Mae Pool (0.5%), Freddie Mac Pool (0.5%). Together they account for 6.8% of the portfolio.
What is MBB's dividend yield?
MBB yields 4.33% based on its trailing 12-month distributions, as of Aug 7, 2026.
How big is MBB?
MBB has $39.1B in assets as of Aug 10, 2026.
What are good alternatives to MBB?
By portfolio overlap, the closest Bond ETFs to MBB are VMBS (17% overlap), AGG (17% overlap), EAGG (13% overlap). Overlap measures the share of portfolio weight both funds hold in the same securities.