BND vs MBB: Holdings Overlap
BNDVanguard Total Bond Market Index Fund
Vanguard · 17360 holdings · $161.4B · as of 2026-03-31
iShares · 11144 holdings · $39.1B · as of 2026-05-31
Holdings snapshots are 61 days apart (BND: 2026-03-31, MBB: 2026-05-31). 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 BND and MBB?
Vanguard Total Bond Market Index Fund (BND, by Vanguard) holds 17360 positions; iShares MBS ETF (MBB, by iShares) holds 11144. They have 1356 holdings in common, and by portfolio weight the two funds are 5.4% identical. In practical terms the pair is lightly overlapping, with most of each portfolio distinct.
- Overlap by Weight
- 5.4%Sum of the smaller weight of each shared holding
- Shared Holdings
- 1356BND holds 17360 · MBB holds 11144
- Weight in Shared Holdings
- BND 7%·MBB 29%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 BND
16004 of 17360 positions (91.8% of the fund) are not held by MBB. Showing the top 30 by weight.
- U.S. Treasury Notes0.48%
- U.S. Treasury Notes0.42%
- U.S. Treasury Notes0.42%
- U.S. Treasury Notes0.42%
- U.S. Treasury Notes0.41%
- U.S. Treasury Notes0.41%
Only in MBB
9788 of 11144 positions (69.2% of the fund) are not held by BND. Showing the top 30 by weight.
- Ginnie Mae0.95%
- Uniform Mortgage-Backed Security, TBA0.83%
- Ginnie Mae0.67%
- Uniform Mortgage-Backed Security, TBA0.64%
- Fannie Mae Pool0.52%
- Ginnie Mae0.46%
Performance
| Fund | 1M | YTD | 1Y | 3Y (ann.) | 5Y (ann.) | 10Y (ann.) | Yield |
|---|---|---|---|---|---|---|---|
| BND | -0.3% | +0.0% | +2.4% | +4.2% | -0.2% | +1.5% | 4.03% |
| MBB | -0.2% | +0.4% | +3.9% | +4.7% | +0.3% | +1.2% | 4.33% |
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 BND vs MBB →
Shared Holdings(1356)
The top 10 shared positions account for 9% of the overlap, led by Uniform Mortgage-Backed Securities, Government National Mortgage Association and Uniform Mortgage-Backed Securities.
| Uniform Mortgage-Backed Securities | 0.06% | 0.12% | 0.06% |
|---|---|---|---|
| Government National Mortgage Association | 0.06% | 0.06% | 0.06% |
| Uniform Mortgage-Backed Securities | 0.05% | 0.30% | 0.05% |
| Fannie Mae Pool | 0.06% | 0.05% | 0.05% |
| Fannie Mae Pool | 0.05% | 0.11% | 0.05% |
| Freddie Mac Pool | 0.05% | 0.22% | 0.05% |
| Government National Mortgage Association | 0.04% | 0.55% | 0.04% |
| Uniform Mortgage-Backed Securities | 0.04% | 1.05% | 0.04% |
| Ginnie Mae II Pool | 0.04% | 0.04% | 0.04% |
| Government National Mortgage Association | 0.04% | 0.10% | 0.04% |
| Government National Mortgage Association | 0.07% | 0.04% | 0.04% |
| Ginnie Mae II Pool | 0.04% | 0.15% | 0.04% |
| Government National Mortgage Association | 0.04% | 0.13% | 0.04% |
| Uniform Mortgage-Backed Securities | 0.04% | 0.24% | 0.04% |
| Uniform Mortgage-Backed Securities | 0.04% | 0.10% | 0.04% |
| Freddie Mac Pool | 0.04% | 0.04% | 0.04% |
| Government National Mortgage Association | 0.04% | 0.15% | 0.04% |
| Uniform Mortgage-Backed Securities | 0.04% | 0.31% | 0.04% |
| Government National Mortgage Association | 0.04% | 0.06% | 0.04% |
| Ginnie Mae II Pool | 0.04% | 0.06% | 0.04% |
| Freddie Mac Pool | 0.03% | 0.04% | 0.03% |
| Uniform Mortgage-Backed Securities | 0.03% | 0.13% | 0.03% |
| Government National Mortgage Association | 0.03% | 0.23% | 0.03% |
| Uniform Mortgage-Backed Securities | 0.03% | 0.10% | 0.03% |
| Uniform Mortgage-Backed Securities | 0.03% | 0.15% | 0.03% |
Showing the top 250 of 1356 shared holdings by overlap weight.
Frequently Asked Questions
How much do BND and MBB overlap?
BND and MBB overlap by 5.4% of portfolio weight. They share 1356 holdings (BND holds 17360 positions and MBB holds 11144), based on each fund's latest SEC-reported holdings.
Is it redundant to own both BND and MBB?
The two portfolios are 5.4% 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 BND and MBB?
The largest positions held by both funds are Uniform Mortgage-Backed Securities, Government National Mortgage Association, Uniform Mortgage-Backed Securities, Fannie Mae Pool and Fannie Mae Pool. Together the top 10 shared positions account for 9% of the total overlap.
What does BND own that MBB doesn't?
16004 positions (91.8% of BND) are unique to BND, led by U.S. Treasury Notes, U.S. Treasury Notes and U.S. Treasury Notes. In the other direction, 9788 positions (69.2% of MBB) are unique to MBB.