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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
16.7 %

1,878 positions appear in both funds. Buying equal dollars of AGG and MBB would leave roughly 16.7% of each dollar exposed to the same underlying securities.

AGG unmatched 81.7% Shared 16.7% MBB unmatched 81.4%

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.

In AGG only
11,388 positions
Shared
1,878 positions
In MBB only
9,266 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
$135.65B
TTM yield
4.13%
Top-10 conc.
4.0%
MBB

iShares MBS ETF

iShares · US Aggregate Bond

89 composite / 100
Expense ratio
0.040%
Net assets
$36.25B
TTM yield
4.46%
Top-10 conc.
6.8%

Sub-score comparison

97
Cost
96
52
Tax efficiency
52
100
Liquidity
100
100
Concentration
100
—
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

1,878 shared in total
# Holding In AGG In MBB Overlap
1 Fannie Mae 0.22% 0.31% 0.22%
2 UMBS, TBA 0.20% 0.34% 0.20%
3 UMBS, TBA 0.16% 0.64% 0.16%
4 Government National Mortgage Association 0.14% 0.95% 0.14%
5 Freddie Mac 0.14% 0.18% 0.14%
6 Government National Mortgage Association 0.14% 0.35% 0.14%
7 UMBS, TBA 0.14% 0.83% 0.14%
8 Fannie Mae 0.13% 0.44% 0.13%
9 Fannie Mae 0.13% 0.52% 0.13%
10 Government National Mortgage Association 0.12% 0.20% 0.12%
11 Government National Mortgage Association 0.12% 0.67% 0.12%
12 Fannie Mae 0.12% 0.22% 0.12%

Only in AGG

11,388 total
  • United States Treasury 0.42%
  • United States Treasury 0.41%
  • United States Treasury 0.41%
  • United States Treasury 0.40%
  • United States Treasury 0.40%
  • United States Treasury 0.39%
  • United States Treasury 0.39%
  • United States Treasury 0.39%
  • United States Treasury 0.39%
  • United States Treasury 0.38%

Only in MBB

9,266 total
  • Fannie Mae 0.33%
  • Fannie Mae 0.28%
  • Fannie Mae 0.23%
  • Fannie Mae 0.21%
  • Freddie Mac 0.20%
  • Freddie Mac 0.19%
  • Fannie Mae 0.17%
  • Fannie Mae 0.17%
  • Fannie Mae 0.16%
  • Freddie Mac 0.15%

Percentages are holdings overlap with the named fund.

Open AGG or MBB 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.