ETF comparison
SPAB vs VMBS
Both US Aggregate Bond.
State Street SPDR Portfolio Aggregate Bond ETF · Vanguard Mortgage-Backed Securities Index Fund ETF Shares
Holdings overlap
492 positions appear in both funds. Buying equal dollars of SPAB and VMBS would leave roughly 9.7% 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
Expense ratios are effectively identical (0.030% vs 0.030%).
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 SPAB vs VMBS.
Top shared holdings
492 shared in total| # | Holding | In SPAB | In VMBS | Overlap |
|---|---|---|---|---|
| 1 | Freddie Mac | 0.20% | 0.24% | 0.20% |
| 2 | Freddie Mac | 0.20% | 0.21% | 0.20% |
| 3 | Freddie Mac | 0.17% | 0.18% | 0.17% |
| 4 | Freddie Mac | 0.16% | 0.23% | 0.16% |
| 5 | Government National Mortgage Association | 0.16% | 0.36% | 0.16% |
| 6 | Fannie Mae | 0.15% | 0.15% | 0.15% |
| 7 | Freddie Mac | 0.14% | 0.20% | 0.14% |
| 8 | Freddie Mac | 0.13% | 0.24% | 0.13% |
| 9 | Fannie Mae | 0.12% | 0.18% | 0.12% |
| 10 | Fannie Mae | 0.12% | 0.18% | 0.12% |
| 11 | Government National Mortgage Association | 0.11% | 0.11% | 0.11% |
| 12 | Government National Mortgage Association | 0.11% | 0.11% | 0.11% |
Only in SPAB
7,793 total- United States Treasury 0.79%
- United States Treasury 0.44%
- United States Treasury 0.43%
- United States Treasury 0.42%
- United States Treasury 0.40%
- United States Treasury 0.40%
- United States Treasury 0.39%
- United States Treasury 0.38%
- United States Treasury 0.37%
- United States Treasury 0.37%
Only in VMBS
4,620 total- Fannie Mae or Freddie Mac 0.52%
- Ginnie Mae II Pool 0.32%
- Ginnie Mae II Pool 0.31%
- Fannie Mae Pool 0.29%
- Ginnie Mae II Pool 0.29%
- Ginnie Mae II Pool 0.29%
- Ginnie Mae II Pool 0.28%
- Freddie Mac Pool 0.27%
- Freddie Mac Pool 0.26%
- Fannie Mae or Freddie Mac 0.25%
Related comparisons
More comparisons with SPAB
- SPAB vs VGLT · Vanguard Long-Term Treasury Index Fund ETF Shares 9.6%
- SPAB vs CGCP · Capital Group Core Plus Income ETF 7.7%
- SPAB vs JCPB · JPMorgan Core Plus Bond ETF 6.2%
- SPAB vs MBB · iShares MBS ETF 5.7%
- SPAB vs TLT · iShares 20+ Year Treasury Bond ETF 4.9%
- SPAB vs BOND · PIMCO Active Bond Exchange-Traded Fund 3.2%
More comparisons with VMBS
- 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%
- VMBS vs VCRB · Vanguard Core Bond ETF 4.6%
- VMBS vs FBND · Fidelity Total Bond ETF 4.5%
- VMBS vs CGCP · Capital Group Core Plus Income ETF 1.8%
Percentages are holdings overlap with the named fund.
Open SPAB 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.