MBB
iShares MBS ETF · BlackRock
Bonds & Treasuries
1Y Return
+4.1%
Expense Ratio
0.04%
AUM
$39B
Dividend Yield
4.34%
Avg Annual Growth (10Y)
-1.1%
Issuer
BlackRock / iShares

Overview

Investment-grade US agency mortgage-backed securities — the Fannie Mae, Freddie Mac and Ginnie Mae bonds that fund America's housing market.

Top Holdings

TickerHoldingWeight
FNMAFannie Mae MBS~44%
FHLMCFreddie Mac MBS~28%
GNMAGinnie Mae MBS~26%
Other agency~2%

Fund Details

Index
Bloomberg US MBS
# Holdings
~13,000
Inception
Mar 2007
Exchange
NYSE Arca
Structure
Open-End Fund
Distribution
Monthly
Avg Annual Growth (10Y)
-1.1%
Avg Annual Yield (10Y)
2.49%

Investment Thesis

Agency mortgages are the second-largest bond sector in America after Treasuries, carrying effective government backing but yielding more because homeowners can refinance whenever it suits them — prepayment risk that investors get paid to bear. MBB is the standard one-ticket route into the sector and a large slice of what AGG and BND already hold; owning it directly is a deliberate overweight on the mortgage spread.

Who It's For

Income investors who want government-quality credit with extra yield and understand the prepayment trade-off. Best in tax-advantaged accounts; monthly payer.

10-Year History

Annual Closing Price
YearClose% Chg
2016$101.50--
2017$101.20-0.3%
2018$99.98-1.2%
2019$103.68+3.7%
2020$105.44+1.7%
2021$102.70-2.6%
2022$88.74-13.6%
2023$90.24+1.7%
2024$89.70-0.6%
2025$91.14+1.6%
Annual Dividend Yield
YearYield
20162.10%
20172.10%
20182.30%
20192.60%
20202.20%
20211.40%
20221.20%
20232.60%
20244.10%
20254.34%
Annual AUM
YearAUM% Chg
2016$10B--
2017$11B+10.0%
2018$13B+18.2%
2019$15B+15.4%
2020$17B+13.3%
2021$19B+11.8%
2022$22B+15.8%
2023$25B+13.6%
2024$29B+16.0%
2025$33B+13.8%

Historical figures are ETFHub estimates modelled from asset-class return patterns and may differ from official fund records. Data as of August 2026.

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