AMUNvsMBBETF Comparison
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abrdn Ultra Short Municipal Income Active ETF (AMUN) belongs to the Municipal Bonds segment. iShares MBS ETF (MBB) is part of the MBS & ABS segment. AMUN's top 2 sector exposures are Municipal and Non-Corporate. In contrast, MBB's top sector exposures are Industrials, Non-Corporate and Finance. AMUN is more expensive with a Total Expense Ratio (TER) of 0.74%, versus 0.04% for MBB. AMUN is up 1.98% year-to-date (YTD) with +$29M 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 AMUN 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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AMUN 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. | AMUN MBB | +0.10%-0.25% | +0.44%-2.30% | +1.98%-1.78% | +2.58%-1.43% | n/a+17.04% | n/a-0.38% |
| Flows | AMUN MBB | +$3M-$3.31B | +$5M-$2.66B | +$29M-$1.79B | +$58M-$5.06B | -+$8.97B | -+$13.89B |
Volatility and drawdown
| 3M | 1Y | 3Y | 5Y | ||
|---|---|---|---|---|---|
| Volatility | AMUN MBB | +0.47%+5.70% | +0.32%+4.61% | n/a+5.73% | n/a+6.66% |
| Max drawdown | AMUN MBB | -0.31%-4.27% | -0.31%-5.38% | n/a-5.38% | n/a-16.94% |
| Max drawdown duration | AMUN MBB | 36d52d | 36d229d | n/a229d | n/a1405d |
Trading data
AMUN | MBB | |
Last sale 10/19/2026 at 1:30 PM | $26.01 | $90.22 |
| Previous close 10/16/2026 | $26.00 | $90.52 |
| Consolidated volume 10/16/2026 | ||
| 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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AMUN
is actively managed and doesn’t replicate an indexAMUN | 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 10/19/2026 at 1:30 PM
Live
Closed
AMUN | MBB | |
|---|---|---|
| Last price | $26.01 | $90.22 |
| 1D performance | +0.02% | -0.34% |
| AuM | $58.20 M | $35.27 B |
| E/R | 0.74% | 0.04% |
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Exposure
Countries
AMUN
USA
27.85%
Other
72.15%
MBB
USA
28.44%
Other
71.56%
Sectors
AMUN
Municipal
27.62%
Other
72.38%
MBB
Industrials
20.61%
Non-Corporate
7.6%
Other
71.79%
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Diversification
AMUN
Total weight of top 15 holdings out of 15
46.38%
MBB
Total weight of top 15 holdings out of 15
16.82%
Top 15 holdings
Data as of August 31, 2026
AMUN
US46640KYU23
3.99%
US230589AB90
3.68%
Chandler Industrial Development Authority, 5% 1sep2052, USD (2022-2)
3.66%
Newark, 4.25% 5may2027, USD (2026)
3.64%
US478232SD45
3.64%
US88035TZV50
3.62%
US7386297S79
3.62%
US64972GU289
3.26%
Mississippi Business Finance Corp., FRN 1nov2032, USD (2007A)
2.97%
US414008CX87
2.67%
Main Street Natural Gas Inc., 4% 1may2052, USD
2.59%
US546598AB98
2.54%
PEFA Inc., 5% 1sep2049, USD (2019)
2.27%
US06964KAB26
2.17%
US20774YV531
2.06%
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 AMUN and MBB
How have the AMUN and MBB ETFs performed in 2026?
As of October 16, 2026, AMUN is up 1.98% year-to-date (YTD), while MBB has lost -1.78%. That puts AMUN better performer ahead so far this year.
Which ETF is attracting more investor money: AMUN or MBB?
Year-to-date, the AMUN ETF saw +$29M in flows, compared to -$1.79B for MBB.
Which ETF is more volatile: AMUN or MBB?
Over the past year, AMUN had a volatility of 0.32%, while MBB experienced 4.61%.
Which ETF is bigger: AMUN or MBB?
As of October 16, 2026, AMUN holds $58.20 M in assets under management (AUM), while MBB manages $35.27 B.
What sectors do the AMUN and MBB ETFs invest in?
AMUN leans toward sectors like Municipal. Meanwhile, MBB focuses on Industrials and Non-Corporate.
What are the top holdings of the AMUN ETF and MBB ETF?
AMUN top holdings include US46640KYU23, US230589AB90 and Chandler Industrial Development Authority, 5% 1sep2052, USD (2022-2). MBB holds in its top three: BlackRock Cash Funds - Institutional, US01F0526982 and US21H0526945.
Which ETF is more diversified: AMUN or MBB?
AMUN holds 68 securities with 46.38% 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 AMUN & 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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