MMHYX vs. AHMFX

Last updated Jun 5, 2026

MMHYX (MFS Municipal High Income Fund) and AHMFX (American High-Income Municipal Bond Fund Class F-2) are both High Yield Muni funds. Over the past 10 years, MMHYX returned 2.85%/yr vs 3.48%/yr for AHMFX. Their correlation of 0.85 suggests significant overlap in exposure. MMHYX charges 0.61%/yr vs 0.42%/yr for AHMFX.

Performance

MMHYX vs. AHMFX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in MFS Municipal High Income Fund (MMHYX) and American High-Income Municipal Bond Fund Class F-2 (AHMFX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, MMHYX achieves a 2.52% return, which is significantly higher than AHMFX's 2.26% return. Over the past 10 years, MMHYX has underperformed AHMFX with an annualized return of 2.85%, while AHMFX has yielded a comparatively higher 3.48% annualized return.

MMHYX

• 1D: -0.13%
• 1M: 0.91%
• YTD: 2.52%
• 6M: 2.92%
• 1Y: 8.29%
• 3Y*: 5.69%
• 5Y*: 0.94%
• 10Y*: 2.85%

AHMFX

• 1D: -0.06%
• 1M: 0.86%
• YTD: 2.26%
• 6M: 2.77%
• 1Y: 8.28%
• 3Y*: 6.37%
• 5Y*: 1.87%
• 10Y*: 3.48%

*Multi-year figures are annualized to reflect compound growth (CAGR)

MMHYX vs. AHMFX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
MMHYX MFS Municipal High Income Fund	2.52%	5.02%	6.72%	5.30%	-14.64%	5.31%	3.39%	9.94%	2.09%	7.66%
AHMFX American High-Income Municipal Bond Fund Class F-2	2.26%	6.03%	6.45%	7.04%	-12.44%	5.49%	4.61%	9.12%	1.80%	9.09%

Correlation

The correlation between MMHYX and AHMFX is 0.89, indicating a strong positive relationship between their price movements. Combining them offers limited diversification - they tend to fall together during downturns.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.89
Correlation (3Y) Calculated over the trailing 3-year period	0.90
Correlation (5Y) Calculated over the trailing 5-year period	0.91
Correlation (10Y) Calculated over the trailing 10-year period	0.88
Correlation (All Time) Calculated using the full available price history since Jan 5, 2009	0.85

The correlation between MMHYX and AHMFX has been stable across timeframes, ranging from 0.85 to 0.91 - a consistent structural relationship.

Return for Risk

MMHYX vs. AHMFX — Risk / Return Rank

Compare risk-adjusted metric ranks to identify better-performing investments over the past 12 months.

MMHYX

MMHYX Risk / Return Rank: 72
MMHYX Sharpe Ratio Rank: 76
MMHYX Sortino Ratio Rank: 85
MMHYX Omega Ratio Rank: 87
MMHYX Calmar Ratio Rank: 61
MMHYX Martin Ratio Rank: 52

AHMFX

AHMFX Risk / Return Rank: 79
AHMFX Sharpe Ratio Rank: 87
AHMFX Sortino Ratio Rank: 92
AHMFX Omega Ratio Rank: 92
AHMFX Calmar Ratio Rank: 68
AHMFX Martin Ratio Rank: 57

The rank (0–100) shows how this investment's returns compare to the risk taken. Higher = better. Based on the past 12 months of data, combining Sharpe, Sortino, and other metrics used by quantitative funds and institutional investors.

MMHYX vs. AHMFX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for MFS Municipal High Income Fund (MMHYX) and American High-Income Municipal Bond Fund Class F-2 (AHMFX). 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.

	MMHYX	AHMFX	Difference
Sharpe ratio: Return per unit of total volatility	2.52	2.82	-0.31
Sortino ratio: Return per unit of downside risk	4.09	4.63	-0.54
Omega ratio: Gain probability vs. loss probability	1.62	1.69	-0.07
Calmar ratio: Return relative to maximum drawdown	2.96	3.12	-0.16
Martin ratio: Return relative to average drawdown	10.42	11.17	-0.75
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

MMHYX vs. AHMFX - Sharpe Ratio Comparison

The current MMHYX Sharpe Ratio is 2.52, which is comparable to the AHMFX Sharpe Ratio of 2.82. The chart below compares the historical Sharpe Ratios of MMHYX and AHMFX, calculated using daily returns over the previous 12 months. A higher Sharpe Ratio indicates better risk-adjusted performance relative to the risk-free rate.

Sharpe Ratios by Period

	MMHYX	AHMFX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.52	2.82	-0.31
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.19	0.39	-0.20
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.59	0.77	-0.18
Sharpe Ratio (All Time) Calculated using the full available price history	1.12	1.54	-0.42

Drawdowns

MMHYX vs. AHMFX - Drawdown Comparison

The maximum MMHYX drawdown since its inception was -23.28%, which is greater than AHMFX's maximum drawdown of -17.65%. Use the drawdown chart below to compare losses from any high point for MMHYX and AHMFX.

Drawdown Indicators

	MMHYX	AHMFX	Difference
Max Drawdown Largest peak-to-trough decline	-23.28%	-17.65%	-5.63%
Max Drawdown (1Y) Largest decline over 1 year	-2.91%	-2.76%	-0.15%
Max Drawdown (3Y) Largest decline over 3 years	-7.71%	-6.20%	-1.51%
Max Drawdown (5Y) Largest decline over 5 years	-19.89%	-17.65%	-2.24%
Max Drawdown (10Y) Largest decline over 10 years	-19.89%	-17.65%	-2.24%
Current Drawdown Current decline from peak	-0.13%	-0.06%	-0.07%
Average Drawdown Average peak-to-trough decline	-2.88%	-2.37%	-0.51%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.83%	0.77%	+0.06%

Volatility

MMHYX vs. AHMFX - Volatility Comparison

MFS Municipal High Income Fund (MMHYX) has a higher volatility of 1.33% compared to American High-Income Municipal Bond Fund Class F-2 (AHMFX) at 1.10%. This indicates that MMHYX's price experiences larger fluctuations and is considered to be riskier than AHMFX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	MMHYX	AHMFX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.33%	1.10%	+0.23%
Volatility (6M) Calculated over the trailing 6-month period	2.48%	2.21%	+0.27%
Volatility (1Y) Calculated over the trailing 1-year period	3.43%	3.05%	+0.38%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	4.96%	4.86%	+0.10%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	4.85%	4.55%	+0.30%

MMHYX vs. AHMFX - Expense Ratio Comparison

MMHYX has a 0.61% expense ratio, which is higher than AHMFX's 0.42% expense ratio.

Dividends

MMHYX vs. AHMFX - Dividend Comparison

MMHYX's dividend yield for the trailing twelve months is around 4.36%, more than AHMFX's 4.12% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
AHMFX American High-Income Municipal Bond Fund Class F-2	4.12%	5.58%	4.04%	2.97%	2.71%	3.44%	3.60%	3.68%	3.88%	4.19%	3.74%	4.19%
MMHYX MFS Municipal High Income Fund	4.36%	5.77%	3.91%	3.59%	3.03%	2.95%	3.57%	3.99%	4.18%	4.38%	4.31%	4.64%

Frequently Asked Questions

Can I hold both MMHYX and AHMFX in my portfolio?

MMHYX and AHMFX have a correlation of 0.89, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, MMHYX or AHMFX?

MMHYX has higher volatility (1.33%) compared to AHMFX (1.10%). In terms of maximum drawdown, MMHYX dropped -23.28% vs AHMFX's -17.65%.

Which has better risk-adjusted returns?

AHMFX currently has the higher Sharpe Ratio (2.82 vs 2.52), 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.