FMUBvsMBBETF Comparison
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Fidelity Municipal Bond Opportunities ETF (FMUB) belongs to the Municipal Bonds segment. iShares MBS ETF (MBB) is part of the MBS & ABS segment. FMUB's top 2 sector exposures are Municipal and Non-Corporate. In contrast, MBB's top sector exposures are Industrials, Non-Corporate and Finance. FMUB is more expensive with a Total Expense Ratio (TER) of 0.3%, versus 0.04% for MBB. FMUB is down -1.19% year-to-date (YTD) with +$148M in YTD flows. MBB performs worse with -1.78% YTD performance, and -$1.79B in YTD flows. Run a side-by-side ETF comparison of FMUB and MBB below, and assess how they stack up in performance, liquidity, risk, exposure, holdings, and more, helping you select the best ETF for your investments.
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FMUB vs MBB performance and flow charts
Performance
Cumulative Flows
Historic performance and flows
Data as of 10/16/2026
| 1M | 3M | YTD | 1Y | 3Y | 5Y | ||
|---|---|---|---|---|---|---|---|
| Perf. | FMUB MBB | -0.32%-0.25% | -3.01%-2.30% | -1.19%-1.78% | -0.73%-1.43% | n/a+17.04% | n/a-0.38% |
| Flows | FMUB MBB | +$44M-$3.31B | +$62M-$2.66B | +$148M-$1.79B | +$164M-$5.06B | -+$8.97B | -+$13.89B |
Volatility and drawdown
| 3M | 1Y | 3Y | 5Y | ||
|---|---|---|---|---|---|
| Volatility | FMUB MBB | +5.00%+5.70% | +3.14%+4.61% | n/a+5.73% | n/a+6.66% |
| Max drawdown | FMUB MBB | -5.46%-4.27% | -6.03%-5.38% | n/a-5.38% | n/a-16.94% |
| Max drawdown duration | FMUB MBB | 92d52d | 102d229d | n/a229d | n/a1405d |
Trading data
FMUB | MBB | |
Last sale 10/16/2026 at 1:30 PM | $49.11 | $90.52 |
| Previous close 10/15/2026 | $49.07 | $90.59 |
| Consolidated volume 10/15/2026 | ||
| Average volume 30 days | ||
| Average discount or premium 30 days | ||
| Average Bid/Ask spread 30 days |
Replication quality
Data as of September 30, 2026
1-year trailing difference
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FMUB
is actively managed and doesn’t replicate an indexFMUB | MBB | |
|---|---|---|
| Tracking error | ||
| Tracking difference | ||
| 1 year cumulative return difference | ||
| Best | ||
| Worst | ||
| Daily return difference | ||
| Average | ||
| Worst | ||
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Main metrics
Last update 10/16/2026 at 1:30 PM
Live
Closed
FMUB | MBB | |
|---|---|---|
| Last price | $49.11 | $90.52 |
| 1D performance | +0.08% | -0.08% |
| AuM | $288.02 M | $35.27 B |
| E/R | 0.3% | 0.04% |
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Exposure
Countries
FMUB
USA
34.21%
Other
65.79%
MBB
USA
28.44%
Other
71.56%
Sectors
FMUB
Municipal
26.63%
Non-Corporate
7.58%
Other
65.79%
MBB
Industrials
20.61%
Non-Corporate
7.6%
Other
71.79%
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Diversification
FMUB
Total weight of top 15 holdings out of 15
18.46%
MBB
Total weight of top 15 holdings out of 15
16.82%
Top 15 holdings
Data as of August 31, 2026
FMUB
Fidelity Municipal Cash Central Fund
7.58%
US54659LDS07
1.66%
Black Belt Energy Gas District, 5% 1jun2031, USD (2026)
0.91%
US56035DJJ28
0.80%
US23503CFM47
0.76%
Florida Housing Finance Corp., 1.8% 1jul2036, USD (2021)
0.75%
San Antonio Electric and Gas Systems, FRN 1feb2055, USD (2026A)
0.75%
US64987KDJ43
0.75%
US84136HCT86
0.72%
US52349EEY23
0.67%
Black Belt Energy Gas District, 5% 1nov2036, USD (2026)
0.66%
US88256FAU66
0.63%
Black Belt Energy Gas District, 5% 1dec2034, USD (2026)
0.61%
Black Belt Energy Gas District, 5% 1oct2033, USD (2026)
0.61%
University of Kansas Hospital Authority, 5.5% 1mar2054, USD (2026A)
0.60%
MBB
BlackRock Cash Funds - Institutional
7.60%
US01F0526982
1.26%
US21H0526945
1.05%
FR SD8146, 2% 1may2051, USD (ABS)
0.98%
US01F0506927
0.87%
US21H0606978
0.63%
G2 MB0025, 5% 20nov2054, USD (ABS)
0.55%
US21H0506988
0.55%
G2 MA7648, 2% 20oct2051, USD (ABS)
0.51%
US36179WTX64
0.50%
FN MA4492, 2% 1dec2051, USD (ABS)
0.49%
US36179WJR07
0.48%
US21H0426955
0.48%
FR SD8140, 2% 1apr2051, USD (ABS)
0.47%
FN MA4465, 2% 1nov2051, USD (ABS)
0.42%
Frequently asked questions about FMUB and MBB
How have the FMUB and MBB ETFs performed in 2026?
As of October 16, 2026, FMUB is down -1.19% year-to-date (YTD), while MBB has lost -1.78%. That puts FMUB better performer ahead so far this year.
Which ETF is attracting more investor money: FMUB or MBB?
Year-to-date, the FMUB ETF saw +$148M in flows, compared to -$1.79B for MBB.
Which ETF is more volatile: FMUB or MBB?
Over the past year, FMUB had a volatility of 3.14%, while MBB experienced 4.61%.
Which ETF is bigger: FMUB or MBB?
As of October 16, 2026, FMUB holds $288.02 M in assets under management (AUM), while MBB manages $35.27 B.
What sectors do the FMUB and MBB ETFs invest in?
FMUB leans toward sectors like Municipal and Non-Corporate. Meanwhile, MBB focuses on Industrials and Non-Corporate.
What are the top holdings of the FMUB ETF and MBB ETF?
FMUB top holdings include Fidelity Municipal Cash Central Fund, US54659LDS07 and Black Belt Energy Gas District, 5% 1jun2031, USD (2026). MBB holds in its top three: BlackRock Cash Funds - Institutional, US01F0526982 and US21H0526945.
Which ETF is more diversified: FMUB or MBB?
FMUB holds 563 securities with 18.46% of its assets in the top 15. MBB has 9405 securities and a top 15 weight of 16.82%.
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Latest news about FMUB & MBB
The Weekly ETF Market Monitor (September 28-October 2, 2026)
October 2, 2026
MBB
NYSE x ETF Central ETF Education Series
March 5, 2024
MBB
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