ETF comparison
MBB vs VMBS
Both US Aggregate Bond.
iShares MBS ETF · Vanguard Mortgage-Backed Securities Index Fund ETF Shares
Holdings overlap
1,201 positions appear in both funds. Buying equal dollars of MBB and VMBS would leave roughly 18.4% of each dollar exposed to the same underlying securities.
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
1,201 shared in total| # | Holding | In MBB | In VMBS | Overlap |
|---|---|---|---|---|
| 1 | Government National Mortgage Association | 0.53% | 0.44% | 0.44% |
| 2 | UMBS, TBA | 0.57% | 0.32% | 0.32% |
| 3 | Government National Mortgage Association | 0.42% | 0.28% | 0.28% |
| 4 | Freddie Mac | 1.07% | 0.27% | 0.27% |
| 5 | UMBS, TBA | 0.50% | 0.26% | 0.26% |
| 6 | Government National Mortgage Association | 0.25% | 0.22% | 0.22% |
| 7 | Freddie Mac | 0.23% | 0.21% | 0.21% |
| 8 | Government National Mortgage Association | 0.32% | 0.21% | 0.21% |
| 9 | Fannie Mae | 0.30% | 0.19% | 0.19% |
| 10 | Freddie Mac | 0.24% | 0.17% | 0.17% |
| 11 | Government National Mortgage Association | 0.20% | 0.17% | 0.17% |
| 12 | Fannie Mae | 0.32% | 0.16% | 0.16% |
Only in MBB
9,950 total- BLACKROCK CASH FUNDS 5.90%
- Government National Mortgage Association 0.55%
- Fannie Mae 0.53%
- Government National Mortgage Association 0.45%
- Fannie Mae 0.45%
- Fannie Mae 0.45%
- Fannie Mae 0.33%
- Fannie Mae 0.33%
- Fannie Mae 0.29%
- Fannie Mae 0.23%
Only in VMBS
3,811 total- Ginnie Mae II Pool 0.29%
- Freddie Mac Pool 0.29%
- Fannie Mae Pool 0.21%
- Fannie Mae or Freddie Mac 0.20%
- Freddie Mac Pool 0.19%
- Freddie Mac Pool 0.19%
- Freddie Mac Pool 0.18%
- Fannie Mae Pool 0.17%
- Fannie Mae Pool 0.16%
- Freddie Mac Pool 0.16%
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.