MMIBX vs. AFB
MMIBX (MFS Municipal Income Fund) and AFB (AllianceBernstein National Municipal Income Fund) are both Municipal Bonds funds. Over the past 10 years, MMIBX returned 1.45%/yr vs 1.57%/yr for AFB. At a 0.28 correlation, their price movements are largely independent. MMIBX charges 1.45%/yr vs 1.56%/yr for AFB.
Performance
MMIBX vs. AFB - Performance Comparison
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Returns By Period
In the year-to-date period, MMIBX achieves a 1.87% return, which is significantly lower than AFB's 8.29% return. Over the past 10 years, MMIBX has underperformed AFB with an annualized return of 1.45%, while AFB has yielded a comparatively higher 1.57% annualized return.
MMIBX
- 1D
- 0.12%
- 1M
- 1.49%
- YTD
- 1.87%
- 6M
- 2.25%
- 1Y
- 6.80%
- 3Y*
- 3.54%
- 5Y*
- 0.04%
- 10Y*
- 1.45%
AFB
- 1D
- 0.44%
- 1M
- 3.91%
- YTD
- 8.29%
- 6M
- 9.40%
- 1Y
- 17.74%
- 3Y*
- 6.60%
- 5Y*
- -1.36%
- 10Y*
- 1.57%
MMIBX vs. AFB - Yearly Performance Comparison
| 2026 (YTD) | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | |
|---|---|---|---|---|---|---|---|---|---|---|
MMIBX MFS Municipal Income Fund | 1.87% | 3.56% | 2.42% | 5.45% | -12.27% | 2.35% | 3.28% | 7.40% | 0.38% | 5.00% |
AFB AllianceBernstein National Municipal Income Fund | 8.29% | 4.41% | 4.10% | 7.41% | -25.93% | 7.25% | 7.80% | 20.13% | -5.43% | 6.15% |
Correlation
The correlation between MMIBX and AFB is 0.37, which is low. Their price movements are largely independent, making them effective diversification partners.
| Correlation | |
|---|---|
Correlation (1Y) Calculated over the trailing 1-year period | 0.37 |
Correlation (3Y) Calculated over the trailing 3-year period | 0.51 |
Correlation (5Y) Calculated over the trailing 5-year period | 0.43 |
Correlation (10Y) Calculated over the trailing 10-year period | 0.36 |
Correlation (All Time) Calculated using the full available price history since Jan 29, 2002 | 0.28 |
The correlation between MMIBX and AFB shifts across timeframes, from 0.28 (all time) to 0.51 (3 years), reflecting how their relationship changes across market environments.
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Return for Risk
MMIBX vs. AFB — Risk / Return Rank
MMIBX
AFB
MMIBX vs. AFB - Risk-Adjusted Trends Comparison
This table presents a comparison of risk-adjusted performance metrics for MFS Municipal Income Fund (MMIBX) and AllianceBernstein National Municipal Income Fund (AFB). 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.
Values are calculated on a 1-year rolling basis and updated daily. Risk-adjusted metrics are more stable over longer periods — use the period switch above to explore them.
| MMIBX | AFB | Difference | |
|---|---|---|---|
| Sharpe ratioReturn per unit of total volatility | -0.06 | ||
| Sortino ratioReturn per unit of downside risk | -0.17 | ||
| Omega ratioGain probability vs. loss probability | 1.53 | 1.43 | +0.10 |
| Calmar ratioReturn relative to maximum drawdown | 2.23 | 2.99 | -0.76 |
| Martin ratioReturn relative to average drawdown | 7.48 | 11.26 | -3.77 |
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Drawdowns
MMIBX vs. AFB - Drawdown Comparison
The maximum MMIBX drawdown since its inception was -17.40%, smaller than the maximum AFB drawdown of -50.98%. Use the drawdown chart below to compare losses from any high point for MMIBX and AFB.
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Drawdown Indicators
| MMIBX | AFB | Difference | |
|---|---|---|---|
Max DrawdownLargest peak-to-trough decline | -17.40% | -50.98% | +33.58% |
Max Drawdown (1Y)Largest decline over 1 year | -3.01% | -5.96% | +2.95% |
Max Drawdown (3Y)Largest decline over 3 years | -7.23% | -16.32% | +9.09% |
Max Drawdown (5Y)Largest decline over 5 years | -17.19% | -35.17% | +17.98% |
Max Drawdown (10Y)Largest decline over 10 years | -17.19% | -35.17% | +17.98% |
Current DrawdownCurrent decline from peak | -0.77% | -7.79% | +7.02% |
Average DrawdownAverage peak-to-trough decline | -2.81% | -8.98% | +6.17% |
Ulcer IndexDepth and duration of drawdowns from previous peaks | 0.89% | 1.58% | -0.69% |
Volatility
MMIBX vs. AFB - Volatility Comparison
The current volatility for MFS Municipal Income Fund (MMIBX) is 0.80%, while AllianceBernstein National Municipal Income Fund (AFB) has a volatility of 2.65%. This indicates that MMIBX experiences smaller price fluctuations and is considered to be less risky than AFB based on this measure. The chart below showcases a comparison of their rolling one-month volatility.
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Volatility by Period
| MMIBX | AFB | Difference | |
|---|---|---|---|
Volatility (1M)Calculated over the trailing 1-month period | 0.80% | 2.65% | -1.85% |
Volatility (6M)Calculated over the trailing 6-month period | 2.32% | 6.02% | -3.70% |
Volatility (1Y)Calculated over the trailing 1-year period | 3.11% | 8.06% | -4.95% |
Volatility (5Y)Calculated over the trailing 5-year period, annualized | 4.41% | 10.97% | -6.56% |
Volatility (10Y)Calculated over the trailing 10-year period, annualized | 4.34% | 11.25% | -6.91% |
MMIBX vs. AFB - Expense Ratio Comparison
MMIBX has a 1.45% expense ratio, which is lower than AFB's 1.56% expense ratio.
Dividends
MMIBX vs. AFB - Dividend Comparison
MMIBX's dividend yield for the trailing twelve months is around 2.95%, less than AFB's 5.03% yield.
| Position | TTM | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
AFB AllianceBernstein National Municipal Income Fund | 5.03% | 4.72% | 3.83% | 3.62% | 5.26% | 4.32% | 4.18% | 3.93% | 4.53% | 4.71% | 5.34% | 5.80% |
MMIBX MFS Municipal Income Fund | 2.95% | 3.81% | 2.51% | 2.05% | 1.42% | 1.45% | 1.86% | 2.45% | 2.68% | 2.67% | 2.87% | 2.98% |
Frequently Asked Questions
MMIBX and AFB have a correlation of 0.37, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.
AFB has higher volatility (2.65%) compared to MMIBX (0.80%). In terms of maximum drawdown, MMIBX dropped -17.40% vs AFB's -50.98%.
AFB currently has the higher Sharpe Ratio (2.21 vs 2.15), 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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