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ETF comparison

AGG vs MBB

Both US Aggregate Bond.

iShares Core U.S. Aggregate Bond ETF · iShares MBS ETF

Holdings overlap

Weighted by ISIN/CUSIP
17.4 %

1,853 positions appear in both funds. Buying equal dollars of AGG and MBB would leave roughly 17.4% of each dollar exposed to the same underlying securities.

AGG only 81.6% Shared 17.4% MBB only 87.0%
In AGG only
11,330 positions
Shared
1,853 positions
In MBB only
9,298 positions

Side by side

AGG

iShares Core U.S. Aggregate Bond ETF

iShares · US Aggregate Bond

89 composite / 100
Expense ratio
0.030%
Net assets
$138.85B
TTM yield
4.01%
Top-10 conc.
7.1%
MBB

iShares MBS ETF

iShares · US Aggregate Bond

88 composite / 100
Expense ratio
0.040%
Net assets
$39.63B
TTM yield
4.30%
Top-10 conc.
11.7%

Sub-score comparison

97
Cost
96
52
Tax efficiency
52
100
Liquidity
100
100
Concentration
98
—
Tracking quality
—
AGG sub-score MBB

Tracking quality isn't part of the composite — see what we don't score for why.

Cost difference

AGG 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 AGG vs MBB.

Top shared holdings

1,853 shared in total
# Holding In AGG In MBB Overlap
1 BlackRock Funds III 0.52% 5.90% 0.52%
2 Fannie Mae 0.23% 0.32% 0.23%
3 UMBS, TBA 0.22% 0.25% 0.22%
4 UMBS, TBA 0.21% 0.50% 0.21%
5 UMBS, TBA 0.17% 0.57% 0.17%
6 UMBS, TBA 0.15% 0.35% 0.15%
7 Government National Mortgage Association 0.14% 0.36% 0.14%
8 Freddie Mac 0.14% 0.35% 0.14%
9 Fannie Mae 0.14% 0.45% 0.14%
10 Fannie Mae 0.13% 0.53% 0.13%
11 Government National Mortgage Association 0.13% 0.20% 0.13%
12 Government National Mortgage Association 0.13% 0.21% 0.13%

Only in AGG

11,330 total
  • United States Treasury 0.46%
  • United States Treasury 0.43%
  • United States Treasury 0.42%
  • United States Treasury 0.42%
  • United States Treasury 0.42%
  • United States Treasury 0.41%
  • United States Treasury 0.41%
  • United States Treasury 0.41%
  • United States Treasury 0.40%
  • United States Treasury 0.40%

Only in MBB

9,298 total
  • Fannie Mae 0.33%
  • Fannie Mae 0.29%
  • Fannie Mae 0.23%
  • Fannie Mae 0.22%
  • Freddie Mac 0.20%
  • Freddie Mac 0.20%
  • Fannie Mae 0.18%
  • Fannie Mae 0.18%
  • Freddie Mac 0.18%
  • Fannie Mae 0.17%

Open AGG or MBB 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.