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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

Weighted by ISIN/CUSIP
9.1 %

477 positions appear in both funds. Buying equal dollars of SPAB and VMBS would leave roughly 9.1% of each dollar exposed to the same underlying securities.

SPAB only 90.0% Shared 9.1% VMBS only 89.6%
In SPAB only
7,851 positions
Shared
477 positions
In VMBS only
4,535 positions

Side by side

SPAB

State Street SPDR Portfolio Aggregate Bond ETF

State Street · US Aggregate Bond

89 composite / 100
Expense ratio
0.030%
Net assets
$9.63B
TTM yield
4.08%
Top-10 conc.
9.3%
VMBS

Vanguard Mortgage-Backed Securities Index Fund ETF Shares

Vanguard · US Aggregate Bond

89 composite / 100
Expense ratio
0.030%
Net assets
$17.34B
TTM yield
4.20%
Top-10 conc.
7.5%

Sub-score comparison

97
Cost
97
52
Tax efficiency
52
99
Liquidity
100
100
Concentration
100
—
Tracking quality
—
SPAB sub-score VMBS

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

477 shared in total
# Holding In SPAB In VMBS Overlap
1 Freddie Mac 0.21% 0.22% 0.21%
2 Freddie Mac 0.17% 0.19% 0.17%
3 Freddie Mac 0.17% 0.25% 0.17%
4 Fannie Mae 0.15% 0.16% 0.15%
5 Freddie Mac 0.15% 0.21% 0.15%
6 Fannie Mae 0.13% 0.19% 0.13%
7 Fannie Mae 0.13% 0.19% 0.13%
8 Government National Mortgage Association 0.12% 0.12% 0.12%
9 Freddie Mac 0.12% 0.14% 0.12%
10 Government National Mortgage Association 0.12% 0.12% 0.12%
11 Fannie Mae 0.12% 0.12% 0.12%
12 Government National Mortgage Association 0.12% 0.15% 0.12%

Only in SPAB

7,851 total
  • State Street Global Advisors 1.15%
  • United States Treasury 0.85%
  • United States Treasury 0.45%
  • United States Treasury 0.44%
  • United States Treasury 0.43%
  • United States Treasury 0.42%
  • United States Treasury 0.39%
  • UMBS, TBA 0.38%
  • United States Treasury 0.37%
  • United States Treasury 0.37%

Only in VMBS

4,535 total
  • Ginnie Mae II Pool 0.44%
  • Fannie Mae or Freddie Mac 0.43%
  • Fannie Mae or Freddie Mac 0.34%
  • Fannie Mae or Freddie Mac 0.32%
  • Ginnie Mae II Pool 0.29%
  • Freddie Mac Pool 0.29%
  • Ginnie Mae II Pool 0.28%
  • Freddie Mac Pool 0.27%
  • Fannie Mae or Freddie Mac 0.26%
  • Ginnie Mae II Pool 0.22%

Open SPAB or VMBS at a brokerage

Both funds trade commission-free at major US brokerages.

Open at Fidelity

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.