PlainIndex
Menu

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

Weighted by ISIN/CUSIP
18.1 %

661 positions appear in both funds. Buying equal dollars of SPAB and SPMB would leave roughly 18.1% of each dollar exposed to the same underlying securities.

SPAB only 81.0% Shared 18.1% SPMB only 80.1%
In SPAB only
7,667 positions
Shared
661 positions
In SPMB only
1,992 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%
SPMB

State Street SPDR Portfolio Mortgage Backed Bond ETF

State Street · US Aggregate Bond

86 composite / 100
Expense ratio
0.040%
Net assets
$7.07B
TTM yield
4.11%
Top-10 conc.
13.6%

Sub-score comparison

97
Cost
96
52
Tax efficiency
52
99
Liquidity
93
100
Concentration
95
—
Tracking quality
—
SPAB sub-score SPMB

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

661 shared in total
# Holding In SPAB In SPMB Overlap
1 Government National Mortgage Association 0.36% 0.52% 0.36%
2 UMBS, TBA 0.38% 0.36% 0.36%
3 Government National Mortgage Association 0.26% 0.45% 0.26%
4 Fannie Mae 0.23% 0.50% 0.23%
5 Freddie Mac 0.22% 0.40% 0.22%
6 Freddie Mac 0.21% 0.22% 0.21%
7 Freddie Mac 0.19% 0.89% 0.19%
8 UMBS, TBA 0.19% 0.28% 0.19%
9 Government National Mortgage Association 0.18% 0.19% 0.18%
10 Freddie Mac 0.17% 0.46% 0.17%
11 Freddie Mac 0.17% 0.30% 0.17%
12 Freddie Mac 0.17% 0.29% 0.17%

Only in SPAB

7,667 total
  • 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%
  • United States Treasury 0.37%
  • United States Treasury 0.37%
  • United States Treasury 0.37%
  • United States Treasury 0.37%

Only in SPMB

1,992 total
  • Freddie Mac 0.92%
  • Fannie Mae 0.83%
  • Government National Mortgage Association 0.43%
  • Fannie Mae 0.40%
  • Fannie Mae 0.40%
  • Freddie Mac 0.39%
  • Government National Mortgage Association 0.39%
  • Government National Mortgage Association 0.38%
  • Fannie Mae 0.38%
  • Government National Mortgage Association 0.37%

Open SPAB or SPMB 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.