MBB vs SCHZ: Holdings Overlap
iShares · 11144 holdings · $39.1B · as of 2026-05-31
SCHZSchwab U.S. Aggregate Bond ETF
Schwab · 12081 holdings · $10.5B · as of 2026-03-31
Holdings snapshots are 61 days apart (MBB: 2026-05-31, SCHZ: 2026-03-31). Weights and index membership change between snapshots, so the true current overlap is typically higher than shown. For funds tracking the same index, the gap can be 5–15 points.
How similar are MBB and SCHZ?
iShares MBS ETF (MBB, by iShares) holds 11144 positions; Schwab U.S. Aggregate Bond ETF (SCHZ, by Schwab) holds 12081. They have 798 holdings in common, and by portfolio weight the two funds are 6.9% identical. In practical terms the pair is lightly overlapping, with most of each portfolio distinct.
- Overlap by Weight
- 6.9%Sum of the smaller weight of each shared holding
- Shared Holdings
- 798MBB holds 11144 · SCHZ holds 12081
- Weight in Shared Holdings
- MBB 26%·SCHZ 10%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
10346 of 11144 positions (72.0% of the fund) are not held by SCHZ. Showing the top 30 by weight.
- Ginnie Mae0.95%
- Uniform Mortgage-Backed Security, TBA0.83%
- Ginnie Mae0.67%
- Uniform Mortgage-Backed Security, TBA0.64%
- Ginnie Mae0.46%
- Fannie Mae Pool0.44%
Only in SCHZ
11283 of 12081 positions (89.1% of the fund) are not held by MBB. Showing the top 30 by weight.
- U.S. Treasury Notes0.44%
- U.S. Treasury Notes0.39%
- U.S. Treasury Notes0.38%
- U.S. Treasury Notes0.38%
- U.S. Treasury Notes0.38%
- U.S. Treasury Notes0.38%
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% |
| SCHZ | -0.2% | +0.1% | +2.5% | +4.2% | -0.2% | +1.4% | 4.20% |
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 SCHZ →
Shared Holdings(798)
The top 10 shared positions account for 12% of the overlap, led by Freddie Mac Pool, Freddie Mac Pool and Ginnie Mae II Pool.
| Freddie Mac Pool | 0.50% | 0.11% | 0.11% |
|---|---|---|---|
| Freddie Mac Pool | 1.05% | 0.11% | 0.11% |
| Ginnie Mae II Pool | 0.16% | 0.09% | 0.09% |
| Freddie Mac Pool | 0.22% | 0.09% | 0.09% |
| Fannie Mae Pool | 0.31% | 0.08% | 0.08% |
| Fannie Mae Pool | 0.12% | 0.08% | 0.08% |
| Freddie Mac Pool | 0.24% | 0.08% | 0.08% |
| Fannie Mae Pool | 0.10% | 0.07% | 0.07% |
| Freddie Mac Pool | 0.08% | 0.07% | 0.07% |
| Fannie Mae Pool | 0.11% | 0.07% | 0.07% |
| Fannie Mae Pool | 0.44% | 0.07% | 0.07% |
| Ginnie Mae II Pool | 0.28% | 0.06% | 0.06% |
| Ginnie Mae II Pool | 0.08% | 0.06% | 0.06% |
| Freddie Mac Pool | 0.08% | 0.06% | 0.06% |
| Fannie Mae Pool | 0.30% | 0.06% | 0.06% |
| Fannie Mae Pool | 0.05% | 0.06% | 0.05% |
| Fannie Mae Pool | 0.05% | 0.08% | 0.05% |
| Fannie Mae Pool | 0.07% | 0.05% | 0.05% |
| Fannie Mae Pool | 0.33% | 0.05% | 0.05% |
| Fannie Mae Pool | 0.07% | 0.05% | 0.05% |
| Ginnie Mae II Pool | 0.10% | 0.05% | 0.05% |
| Freddie Mac Pool | 0.05% | 0.05% | 0.05% |
| Fannie Mae Pool | 0.07% | 0.05% | 0.05% |
| Fannie Mae Pool | 0.52% | 0.05% | 0.05% |
| Fannie Mae Pool | 0.09% | 0.04% | 0.04% |
Showing the top 250 of 798 shared holdings by overlap weight.
Frequently Asked Questions
How much do MBB and SCHZ overlap?
MBB and SCHZ overlap by 6.9% of portfolio weight. They share 798 holdings (MBB holds 11144 positions and SCHZ holds 12081), based on each fund's latest SEC-reported holdings.
Is it redundant to own both MBB and SCHZ?
The two portfolios are 6.9% 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 SCHZ?
The largest positions held by both funds are Freddie Mac Pool, Freddie Mac Pool, Ginnie Mae II Pool, Freddie Mac Pool and Fannie Mae Pool. Together the top 10 shared positions account for 12% of the total overlap.
What does MBB own that SCHZ doesn't?
10346 positions (72.0% of MBB) are unique to MBB, led by Ginnie Mae, Uniform Mortgage-Backed Security, TBA and Ginnie Mae. In the other direction, 11283 positions (89.1% of SCHZ) are unique to SCHZ.