ETF comparison
SPAB vs SPMB
Both US Aggregate Bond.
State Street SPDR Portfolio Aggregate Bond ETF · State Street SPDR Portfolio Mortgage Backed Bond ETF
Holdings overlap
681 positions appear in both funds. Buying equal dollars of SPAB and SPMB would leave roughly 18.0% 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
SPAB is 1 bps cheaper than SPMB. On a $100,000 position that's about $10/yr more in fees for SPMB.
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 SPMB.
Top shared holdings
681 shared in total| # | Holding | In SPAB | In SPMB | Overlap |
|---|---|---|---|---|
| 1 | Government National Mortgage Association | 0.28% | 0.36% | 0.28% |
| 2 | UMBS, TBA | 0.27% | 0.45% | 0.27% |
| 3 | UMBS, TBA | 0.23% | 0.63% | 0.23% |
| 4 | Fannie Mae | 0.21% | 0.47% | 0.21% |
| 5 | Government National Mortgage Association | 0.21% | 0.42% | 0.21% |
| 6 | Freddie Mac | 0.20% | 1.17% | 0.20% |
| 7 | Freddie Mac | 0.20% | 0.36% | 0.20% |
| 8 | Freddie Mac | 0.20% | 0.33% | 0.20% |
| 9 | Government National Mortgage Association | 0.17% | 0.17% | 0.17% |
| 10 | Freddie Mac | 0.17% | 0.76% | 0.17% |
| 11 | Freddie Mac | 0.17% | 0.43% | 0.17% |
| 12 | Freddie Mac | 0.16% | 0.29% | 0.16% |
Only in SPAB
7,604 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 SPMB
2,018 total- Fannie Mae 0.79%
- Fannie Mae 0.49%
- Government National Mortgage Association 0.41%
- Fannie Mae 0.37%
- Government National Mortgage Association 0.36%
- Fannie Mae 0.35%
- Fannie Mae 0.35%
- Freddie Mac 0.35%
- Government National Mortgage Association 0.34%
- Government National Mortgage Association 0.32%
Related comparisons
More comparisons with SPAB
- SPAB vs BLV · Vanguard Long-Term Bond Index Fund ETF Shares 17.1%
- SPAB vs BIV · Vanguard Intermediate-Term Bond Index Fund ETF Shares 16.8%
- SPAB vs VCRB · Vanguard Core Bond ETF 15.8%
- SPAB vs DFCF · Dimensional Core Fixed Income ETF 15.2%
- SPAB vs VGSH · Vanguard Short-Term Treasury Index Fund ETF Shares 14.6%
- SPAB vs FBND · Fidelity Total Bond ETF 14.6%
More comparisons with SPMB
- SPMB vs MBB · iShares MBS ETF 14.5%
- SPMB vs SCHZ · Schwab U.S. Aggregate Bond ETF 8.9%
- SPMB vs BND · Vanguard Total Bond Market Index Fund ETF Shares 5.9%
- SPMB vs AGG · iShares Core U.S. Aggregate Bond ETF 5.5%
- SPMB vs VCRB · Vanguard Core Bond ETF 4.9%
- SPMB vs EAGG · iShares ESG U.S. Aggregate Bond ETF 3.9%
Percentages are holdings overlap with the named fund.
Open SPAB or SPMB 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.