MUB vs. MFLX
MUB (iShares National AMT-Free Muni Bond ETF) and MFLX (First Trust Flexible Municipal High Income ETF) are both Municipal Bonds funds. MUB is passively managed, while MFLX is actively managed. Over the past 5 years, MUB returned 0.86%/yr vs -0.03%/yr for MFLX. At a 0.36 correlation, their price movements are largely independent. MUB charges 0.07%/yr vs 0.88%/yr for MFLX.
Performance
MUB vs. MFLX - Performance Comparison
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Returns By Period
In the year-to-date period, MUB achieves a 1.24% return, which is significantly lower than MFLX's 3.33% return.
MUB
- 1D
- -0.08%
- 1M
- 0.56%
- YTD
- 1.24%
- 6M
- 1.74%
- 1Y
- 6.95%
- 3Y*
- 3.43%
- 5Y*
- 0.86%
- 10Y*
- 2.00%
MFLX
- 1D
- -0.06%
- 1M
- 1.21%
- YTD
- 3.33%
- 6M
- 3.84%
- 1Y
- 9.22%
- 3Y*
- 5.48%
- 5Y*
- -0.03%
- 10Y*
- —
MUB vs. MFLX - Yearly Performance Comparison
| 2026 (YTD) | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | |
|---|---|---|---|---|---|---|---|---|---|---|
MUB iShares National AMT-Free Muni Bond ETF | 1.24% | 3.78% | 1.26% | 5.56% | -7.34% | 1.02% | 5.12% | 7.06% | 0.93% | 4.72% |
MFLX First Trust Flexible Municipal High Income ETF | 3.33% | 3.94% | 3.74% | 8.98% | -19.94% | 8.43% | 7.19% | 16.89% | -4.66% | 5.57% |
Correlation
The correlation between MUB and MFLX is 0.58, which is moderate. They share some common price drivers but move independently often enough to provide real diversification benefit when combined.
| Correlation | |
|---|---|
Correlation (1Y) Calculated over the trailing 1-year period | 0.58 |
Correlation (3Y) Calculated over the trailing 3-year period | 0.38 |
Correlation (5Y) Calculated over the trailing 5-year period | 0.36 |
Correlation (All Time) Calculated using the full available price history since Sep 30, 2016 | 0.36 |
Over the past year, MUB and MFLX have become more correlated (0.58) than their long-term average of 0.36, meaning their price movements have been converging.
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Return for Risk
MUB vs. MFLX — Risk / Return Rank
MUB
MFLX
MUB vs. MFLX - Risk-Adjusted Trends Comparison
This table presents a comparison of risk-adjusted performance metrics for iShares National AMT-Free Muni Bond ETF (MUB) and First Trust Flexible Municipal High Income ETF (MFLX). Risk-adjusted metrics are performance indicators that assess an investment's returns in relation to its risk, enabling a more accurate comparison of different investment options.
| MUB | MFLX | Difference | |
|---|---|---|---|
| Sharpe ratioReturn per unit of total volatility | +0.13 | ||
| Sortino ratioReturn per unit of downside risk | +0.03 | ||
| Omega ratioGain probability vs. loss probability | 1.50 | 1.49 | +0.01 |
| Calmar ratioReturn relative to maximum drawdown | 2.50 | 2.97 | -0.47 |
| Martin ratioReturn relative to average drawdown | 8.85 | 11.95 | -3.10 |
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month. | |||
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Sharpe Ratios by Period
| MUB | MFLX | Difference | |
|---|---|---|---|
Sharpe Ratio (1Y)Calculated over the trailing 1-year period | 2.39 | 2.27 | +0.13 |
Sharpe Ratio (5Y)Calculated over the trailing 5-year period | 0.21 | -0.00 | +0.22 |
Sharpe Ratio (10Y)Calculated over the trailing 10-year period | 0.41 | — | — |
Sharpe Ratio (All Time)Calculated using the full available price history | 0.58 | 0.19 | +0.39 |
Drawdowns
MUB vs. MFLX - Drawdown Comparison
The maximum MUB drawdown since its inception was -13.68%, smaller than the maximum MFLX drawdown of -26.76%. Use the drawdown chart below to compare losses from any high point for MUB and MFLX.
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Drawdown Indicators
| MUB | MFLX | Difference | |
|---|---|---|---|
Max DrawdownLargest peak-to-trough decline | -13.68% | -26.76% | +13.08% |
Max Drawdown (1Y)Largest decline over 1 year | -2.79% | -3.11% | +0.32% |
Max Drawdown (3Y)Largest decline over 3 years | -5.34% | -8.18% | +2.84% |
Max Drawdown (5Y)Largest decline over 5 years | -11.88% | -25.88% | +14.00% |
Max Drawdown (10Y)Largest decline over 10 years | -13.68% | — | — |
Current DrawdownCurrent decline from peak | -0.70% | -3.78% | +3.08% |
Average DrawdownAverage peak-to-trough decline | -2.23% | -8.17% | +5.94% |
Ulcer IndexDepth and duration of drawdowns from previous peaks | 0.79% | 0.77% | +0.02% |
Volatility
MUB vs. MFLX - Volatility Comparison
The current volatility for iShares National AMT-Free Muni Bond ETF (MUB) is 0.97%, while First Trust Flexible Municipal High Income ETF (MFLX) has a volatility of 1.41%. This indicates that MUB experiences smaller price fluctuations and is considered to be less risky than MFLX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.
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Volatility by Period
| MUB | MFLX | Difference | |
|---|---|---|---|
Volatility (1M)Calculated over the trailing 1-month period | 0.97% | 1.41% | -0.44% |
Volatility (6M)Calculated over the trailing 6-month period | 2.22% | 2.98% | -0.76% |
Volatility (1Y)Calculated over the trailing 1-year period | 2.92% | 4.08% | -1.16% |
Volatility (5Y)Calculated over the trailing 5-year period, annualized | 4.06% | 10.36% | -6.30% |
Volatility (10Y)Calculated over the trailing 10-year period, annualized | 4.92% | 11.29% | -6.37% |
MUB vs. MFLX - Expense Ratio Comparison
MUB has a 0.07% expense ratio, which is lower than MFLX's 0.88% expense ratio.
Dividends
MUB vs. MFLX - Dividend Comparison
MUB's dividend yield for the trailing twelve months is around 3.17%, less than MFLX's 4.08% yield.
| Position | TTM | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
MFLX First Trust Flexible Municipal High Income ETF | 4.08% | 4.06% | 3.81% | 3.65% | 4.27% | 3.69% | 3.21% | 2.94% | 3.74% | 3.80% | 0.98% | 0.00% |
MUB iShares National AMT-Free Muni Bond ETF | 3.17% | 3.14% | 3.01% | 2.65% | 2.11% | 1.81% | 2.11% | 2.42% | 2.46% | 2.26% | 2.21% | 2.51% |
Frequently Asked Questions
MUB and MFLX have a correlation of 0.58, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.
MFLX has higher volatility (1.41%) compared to MUB (0.97%). In terms of maximum drawdown, MUB dropped -13.68% vs MFLX's -26.76%.
On 5-year performance, MUB leads with 0.86% vs -0.03% for MFLX. On fees, MUB is cheaper at 0.07% per year. On volatility, MUB has been the lower-risk option at 0.97%. The better choice depends on whether you care most about return, fees, risk, or income.
Over the 5-year period, MUB has performed better with a 0.86% return vs -0.03%. Past performance does not guarantee future results, so compare this with risk, fees, and fund exposure.
MUB is cheaper with a 0.07% expense ratio, compared with 0.88% for MFLX.
MFLX has the higher dividend yield at 4.08%, compared with 3.17% for MUB.
They also come from different issuers: iShares and First Trust. Their fees differ too: 0.07% for MUB and 0.88% for MFLX.
MUB currently has the higher Sharpe Ratio (2.39 vs 2.27), meaning it's delivered slightly more return per unit of risk over the trailing 12 months. However, this ranking shifts over time - use the Risk/Return Score above for a more comprehensive view that combines Sharpe, Sortino, and other measures used by quantitative funds.
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