ETF comparison
MBB vs VMBS
Both US Aggregate Bond.
iShares MBS ETF · Vanguard Mortgage-Backed Securities Index Fund ETF Shares
Holdings overlap
1,212 positions appear in both funds. Buying equal dollars of MBB and VMBS would leave roughly 17.2% of each dollar exposed to the same underlying securities.
Unmatched is the part of a fund's weight the other fund doesn't match: names only it holds, plus any extra weight it puts in names both funds hold.
Side by side
Sub-score comparison
Tracking quality isn't part of the composite — see what we don't score for why.
Cost difference
VMBS is 1 bps cheaper than MBB. On a $100,000 position that's about $10/yr more in fees for MBB.
Fee figure is the annual expense charged on $100,000. To see how the gap compounds over a multi-decade holding period, open the cost calculator pre-filled with MBB vs VMBS.
Top shared holdings
1,212 shared in total| # | Holding | In MBB | In VMBS | Overlap |
|---|---|---|---|---|
| 1 | Government National Mortgage Association | 0.55% | 0.32% | 0.32% |
| 2 | Government National Mortgage Association | 0.95% | 0.29% | 0.29% |
| 3 | Freddie Mac | 1.05% | 0.26% | 0.26% |
| 4 | Freddie Mac | 0.22% | 0.20% | 0.20% |
| 5 | UMBS, TBA | 0.34% | 0.20% | 0.20% |
| 6 | Government National Mortgage Association | 0.31% | 0.20% | 0.20% |
| 7 | Fannie Mae | 0.30% | 0.18% | 0.18% |
| 8 | Freddie Mac | 0.24% | 0.16% | 0.16% |
| 9 | Government National Mortgage Association | 0.20% | 0.16% | 0.16% |
| 10 | Government National Mortgage Association | 0.67% | 0.15% | 0.15% |
| 11 | UMBS, TBA | 0.83% | 0.15% | 0.15% |
| 12 | Fannie Mae | 0.15% | 0.18% | 0.15% |
Only in MBB
9,932 total- Government National Mortgage Association 0.53%
- Fannie Mae 0.52%
- Government National Mortgage Association 0.46%
- Fannie Mae 0.44%
- Fannie Mae 0.44%
- Fannie Mae 0.33%
- Fannie Mae 0.33%
- Government National Mortgage Association 0.28%
- Fannie Mae 0.28%
- Fannie Mae 0.23%
Only in VMBS
3,900 total- Ginnie Mae II Pool 0.36%
- Fannie Mae Pool 0.29%
- Freddie Mac Pool 0.27%
- Freddie Mac Pool 0.27%
- Fannie Mae or Freddie Mac 0.25%
- Freddie Mac Pool 0.24%
- Freddie Mac Pool 0.24%
- Ginnie Mae II Pool 0.20%
- Fannie Mae Pool 0.20%
- Ginnie Mae II Pool 0.19%
Related comparisons
More comparisons with MBB
- MBB vs AGG · iShares Core U.S. Aggregate Bond ETF 16.7%
- MBB vs SPMB · State Street SPDR Portfolio Mortgage Backed Bond ETF 14.5%
- MBB vs EAGG · iShares ESG U.S. Aggregate Bond ETF 12.9%
- MBB vs IUSB · iShares Core Universal USD Bond ETF 9.0%
- MBB vs SCHZ · Schwab U.S. Aggregate Bond ETF 6.8%
- MBB vs SPAB · State Street SPDR Portfolio Aggregate Bond ETF 5.7%
More comparisons with VMBS
- VMBS vs BND · Vanguard Total Bond Market Index Fund ETF Shares 15.5%
- VMBS vs SCHZ · Schwab U.S. Aggregate Bond ETF 10.9%
- VMBS vs SPAB · State Street SPDR Portfolio Aggregate Bond ETF 9.7%
- VMBS vs EAGG · iShares ESG U.S. Aggregate Bond ETF 7.7%
- VMBS vs AGG · iShares Core U.S. Aggregate Bond ETF 7.6%
- VMBS vs IUSB · iShares Core Universal USD Bond ETF 4.7%
Percentages are holdings overlap with the named fund.
Open MBB or VMBS at a brokerage
Both funds trade commission-free at major US brokerages.
Affiliate links — opening an account through these earns PlainIndex a one-time referral. Scoring is computed before any affiliate consideration; see our methodology and funding disclosure.
Holdings overlap is the sum of min(weight_a, weight_b) over positions
matched on ISIN (CUSIP fallback). Methodology: see
/methodology/.
Comparing two funds doesn't endorse swapping one for the other. Tax-lot history, account type, and personal goals matter — PlainIndex publishes data and methodology, not investment advice.