iShares MBS ETF

iShares MBS ETF

About

iShares MBS ETF (US4642885887) is a US-listed bond ETF tracking the Bloomberg U.S. MBS Index. With a expense ratio of 0.04%, it ranks among the lowest-cost options in its category, paying distributions. The fund holds 11,194 positions across 1 region with 39.6B in assets.

Score Breakdown

Scores are scaled 1–10 on a logarithmic curve relative to all ETFs in the database. Last updated: Jun 22, 2026
Component Score Details
Cost (30%) 9.3 Tracking Difference: 8.9 · TD Consistency: — · Expense Ratio: 10.0
Liquidity (25%) 10.0 Assets Under Management

Data sources: provider factsheets, exchange data, and NAV history. Information for educational purposes only — not investment advice.

Ticker MBB
ISIN
Fund Size $39.6B
Issuer iShares
Distribution Pays Distributions
Replication Physical
Inception Mar 2007
Base Currency USD
Index Bloomberg U.S. MBS Index
Asset Class Bonds
Category Securitized Bond

Costs

9.3
This fund has low total costs, with competitive tracking and expense ratios.

Cost Metrics Explained

What expense ratio, tracking difference, and TD consistency measure

Expense ratio (Total Expense Ratio) is the annual fee the fund charges, deducted from assets. It’s the headline cost, but not the full picture.

Tracking Difference measures how much the fund actually lags (or leads) its benchmark index per year. This is the single best measure of true cost — it captures the expense ratio plus all other drags like sampling error and tax withholding. A lower (or negative) value is better.

TD Consistency measures how stable the tracking difference is from year to year. A low value means predictable, reliable costs; a high value means costs can vary significantly.
Expense Ratio0.00%
 
Metric Value
Expense Ratio 0.04%

Cumulative Returns

Performance across different time periods.
Year to Date+0.00%
1 Year+0.00%
3 Years+0.00%
5 Years+0.00%
Inception+0.00%
 
Period Cumulative Return
1 Month —
3 Months —
6 Months —
1 Year +6.79%
3 Years +4.34%
5 Years +0.42%
10 Years +1.36%
YTD +0.81%
Since Inception +2.69%

Holdings

This fund invests into 11,194 individual investments.
#1
BLACKROCK CASH CL INST SL AGENCY
6.05%
#2
Freddie Mac Pool
1.02%
#3
Ginnie Mae II Pool
0.93%
#4
GNMA2 30YR TBA(REG C)
0.88%
#5
UMBS 30YR TBA(REG A)
0.87%
#6
UMBS 30YR TBA(REG A)
0.67%
#7
Ginnie Mae II Pool
0.53%
#8
Ginnie Mae II Pool
0.53%
#9
GNMA2 30YR
0.52%
#10
Fannie Mae Pool
0.51%
View all holdings (50)
# Holding Ticker Weight
1 BLACKROCK CASH CL INST SL AGENCY — 605.26%
2 Freddie Mac Pool — 101.59%
3 Ginnie Mae II Pool — 92.79%
4 GNMA2 30YR TBA(REG C) — 88.05%
5 UMBS 30YR TBA(REG A) — 87.41%
6 UMBS 30YR TBA(REG A) — 67.23%
7 Ginnie Mae II Pool — 53.39%
8 Ginnie Mae II Pool — 52.65%
9 GNMA2 30YR — 51.70%
10 Fannie Mae Pool — 50.85%
11 Freddie Mac Pool — 48.69%
12 GNMA2 30YR TBA(REG C) — 46.53%
13 GNMA2 30YR TBA(REG C) — 44.78%
14 Ginnie Mae II Pool — 44.20%
15 FNMA 30YR UMBS — 43.08%
16 FNMA 30YR UMBS SUPER — 42.34%
17 Ginnie Mae II Pool — 39.60%
18 Ginnie Mae II Pool — 35.26%
19 Ginnie Mae II Pool — 34.39%
20 UMBS 30YR TBA(REG A) — 32.45%
21 FNMA 30YR UMBS SUPER — 31.75%
22 Fannie Mae Pool — 31.71%
23 Fannie Mae Pool — 30.45%
24 Ginnie Mae II Pool — 30.20%
25 Ginnie Mae II Pool — 29.38%
26 Fannie Mae Pool — 28.72%
27 FNMA 30YR UMBS — 27.50%
28 Ginnie Mae II Pool — 27.41%
29 Ginnie Mae II Pool — 27.14%
30 Ginnie Mae II Pool — 26.85%
31 Ginnie Mae II Pool — 26.71%
32 UMBS 15YR TBA(REG B) — 24.95%
33 UMBS 15YR TBA(REG B) — 24.92%
34 FHLMC 30YR UMBS SUPER — 23.63%
35 Freddie Mac Pool — 23.17%
36 FNMA 30YR UMBS SUPER — 22.05%
37 Ginnie Mae II Pool — 21.98%
38 Ginnie Mae II Pool — 21.71%
39 Freddie Mac Pool — 21.59%
40 Freddie Mac Pool — 21.00%
41 FNMA 30YR UMBS SUPER — 20.96%
42 FHLMC 30YR UMBS — 20.90%
43 FNMA 30YR UMBS — 20.37%
44 FNMA 30YR UMBS — 20.06%
45 FNMA 30YR UMBS SUPER — 19.35%
46 FNMA 30YR UMBS SUPER — 19.15%
47 Ginnie Mae II Pool — 19.09%
48 FHLMC 30YR UMBS SUPER — 19.05%
49 FHLMC 30YR UMBS SUPER — 18.62%
50 FNMA 30YR UMBS — 18.34%

Sectors

Allocation by industry sector.
 
Sector Weight
Unknown 7357.00%
Securitized Bonds 2756.00%

Regions

Geographic allocation by country of risk.
 
Country Weight
UNKNOWN 7131.00%
United States 2869.00%

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