MBB vs AGG: Holdings Overlap
iShares · 11144 holdings · $39.1B · as of 2026-05-31
AGGiShares Core U.S. Aggregate Bond ETF
iShares · 13266 holdings · $137.7B · as of 2026-05-31
How similar are MBB and AGG?
iShares MBS ETF (MBB, by iShares) holds 11144 positions; iShares Core U.S. Aggregate Bond ETF (AGG, by iShares) holds 13266. They have 1878 holdings in common, and by portfolio weight the two funds are 16.7% identical. In practical terms the pair is lightly overlapping, with most of each portfolio distinct.
- Overlap by Weight
- 16.7%Sum of the smaller weight of each shared holding
- Shared Holdings
- 1878MBB holds 11144 · AGG holds 13266
- Weight in Shared Holdings
- MBB 57%·AGG 18%Share of each fund's weight in stocks both funds own
Based on each fund's latest official holdings. How is this calculated?
What makes each fund different
Only in MBB
9266 of 11144 positions (40.9% of the fund) are not held by AGG. Showing the top 30 by weight.
- Fannie Mae Pool0.33%
- Fannie Mae Pool0.28%
- Fannie Mae Pool0.23%
- Fannie Mae Pool0.21%
- Freddie Mac Pool0.20%
- Freddie Mac Pool0.19%
Only in AGG
11388 of 13266 positions (80.5% of the fund) are not held by MBB. Showing the top 30 by weight.
- U.S. Treasury Notes0.42%
- U.S. Treasury Notes0.41%
- U.S. Treasury Notes0.41%
- U.S. Treasury Notes0.40%
- U.S. Treasury Notes0.40%
- U.S. Treasury Notes0.39%
Performance
| Fund | 1M | YTD | 1Y | 3Y (ann.) | 5Y (ann.) | 10Y (ann.) | Yield |
|---|---|---|---|---|---|---|---|
| MBB | -0.2% | +0.4% | +3.9% | +4.7% | +0.3% | +1.2% | 4.33% |
| AGG | -0.3% | +0.0% | +2.4% | +4.2% | -0.2% | +1.4% | 4.04% |
Total returns including dividends, from adjusted daily closes as of 2026-08-07. 3Y/5Y/10Y are annualized. Yield is trailing-12-month distributions over the last close. Past performance does not predict future results.
Project the growth of $10,000 in MBB vs AGG →
Shared Holdings(1878)
The top 10 shared positions account for 9% of the overlap, led by Fannie Mae Pool, Uniform Mortgage-Backed Security, TBA and Uniform Mortgage-Backed Security, TBA.
| Fannie Mae Pool | 0.31% | 0.22% | 0.22% |
|---|---|---|---|
| Uniform Mortgage-Backed Security, TBA | 0.34% | 0.20% | 0.20% |
| Uniform Mortgage-Backed Security, TBA | 0.64% | 0.16% | 0.16% |
| Ginnie Mae | 0.95% | 0.14% | 0.14% |
| Freddie Mac Pool | 0.18% | 0.14% | 0.14% |
| Ginnie Mae II Pool | 0.35% | 0.14% | 0.14% |
| Uniform Mortgage-Backed Security, TBA | 0.83% | 0.14% | 0.14% |
| Fannie Mae Pool | 0.44% | 0.13% | 0.13% |
| Fannie Mae Pool | 0.52% | 0.13% | 0.13% |
| Ginnie Mae II Pool | 0.20% | 0.12% | 0.12% |
| Ginnie Mae | 0.67% | 0.12% | 0.12% |
| Fannie Mae Pool | 0.22% | 0.12% | 0.12% |
| Uniform Mortgage-Backed Security, TBA | 0.26% | 0.12% | 0.12% |
| Ginnie Mae II Pool | 0.45% | 0.12% | 0.12% |
| Ginnie Mae II Pool | 0.19% | 0.11% | 0.11% |
| Ginnie Mae II Pool | 0.30% | 0.11% | 0.11% |
| Ginnie Mae II Pool | 0.53% | 0.11% | 0.11% |
| Ginnie Mae II Pool | 0.16% | 0.11% | 0.11% |
| Fannie Mae Pool | 0.17% | 0.11% | 0.11% |
| Ginnie Mae II Pool | 0.55% | 0.11% | 0.11% |
| Ginnie Mae | 0.18% | 0.10% | 0.10% |
| Ginnie Mae | 0.23% | 0.10% | 0.10% |
| Ginnie Mae II Pool | 0.28% | 0.10% | 0.10% |
| Ginnie Mae II Pool | 0.36% | 0.10% | 0.10% |
| Ginnie Mae II Pool | 0.28% | 0.09% | 0.09% |
Showing the top 250 of 1878 shared holdings by overlap weight.
Frequently Asked Questions
How much do MBB and AGG overlap?
MBB and AGG overlap by 16.7% of portfolio weight. They share 1878 holdings (MBB holds 11144 positions and AGG holds 13266), based on each fund's latest SEC-reported holdings.
Is it redundant to own both MBB and AGG?
The two portfolios are 16.7% identical by weight. Owning both is not redundant. Most of each portfolio is distinct, so the funds can serve different roles.
What are the biggest shared holdings of MBB and AGG?
The largest positions held by both funds are Fannie Mae Pool, Uniform Mortgage-Backed Security, TBA, Uniform Mortgage-Backed Security, TBA, Ginnie Mae and Freddie Mac Pool. Together the top 10 shared positions account for 9% of the total overlap.
What does MBB own that AGG doesn't?
9266 positions (40.9% of MBB) are unique to MBB, led by Fannie Mae Pool, Fannie Mae Pool and Fannie Mae Pool. In the other direction, 11388 positions (80.5% of AGG) are unique to AGG.