MMIBX vs. FMBIX

Last updated Apr 3, 2026

Compare and contrast key facts about MFS Municipal Income Fund (MMIBX) and Fidelity Municipal Bond Index Fund (FMBIX).

MMIBX is managed by MFS. It was launched on Dec 28, 1986. FMBIX is managed by Fidelity. It was launched on Jul 11, 2019.

Performance

MMIBX vs. FMBIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in MFS Municipal Income Fund (MMIBX) and Fidelity Municipal Bond Index Fund (FMBIX). The values are adjusted to include any dividend payments, if applicable.

MMIBX vs. FMBIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019
MMIBX MFS Municipal Income Fund	-0.25%	3.56%	2.42%	5.45%	-12.27%	2.35%	3.28%	2.05%
FMBIX Fidelity Municipal Bond Index Fund	0.00%	0.60%	1.32%	5.89%	-10.00%	1.14%	3.10%	1.48%

Returns By Period

MMIBX

• 1D: 0.37%
• 1M: -1.33%
• YTD: -0.25%
• 6M: 0.98%
• 1Y: 2.75%
• 3Y*: 2.84%
• 5Y*: 0.00%
• 10Y*: 1.45%

FMBIX

• 1D: —
• 1M: —
• YTD: —
• 6M: —
• 1Y: —
• 3Y*: —
• 5Y*: —
• 10Y*: —

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

MMIBX vs. FMBIX - Expense Ratio Comparison

MMIBX has a 1.45% expense ratio, which is higher than FMBIX's 0.07% expense ratio.

MMIBX

MFS Municipal Income Fund

FMBIX

Fidelity Municipal Bond Index Fund

Return for Risk

MMIBX vs. FMBIX — Risk / Return Rank

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

MMIBX

MMIBX Risk / Return Rank: 13
MMIBX Sharpe Ratio Rank: 13
MMIBX Sortino Ratio Rank: 11
MMIBX Omega Ratio Rank: 18
MMIBX Calmar Ratio Rank: 13
MMIBX Martin Ratio Rank: 12

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.

MMIBX vs. FMBIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for MFS Municipal Income Fund (MMIBX) and Fidelity Municipal Bond Index Fund (FMBIX). 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.

	MMIBX	FMBIX	Difference
Sharpe ratio Return per unit of total volatility	0.50	—	—
Sortino ratio Return per unit of downside risk	0.70	—	—
Omega ratio Gain probability vs. loss probability	1.14	—	—
Calmar ratio Return relative to maximum drawdown	0.60	—	—
Martin ratio Return relative to average drawdown	1.74	—	—
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

Sharpe Ratios by Period

	MMIBX	FMBIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	0.50	—	—
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.00	—	—
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.34	—	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.81	—	—

Correlation

The correlation between MMIBX and FMBIX is 0.83, which is considered to be high. That indicates a strong positive relationship between their price movements. Having highly-correlated positions in a portfolio may signal a lack of diversification, potentially leading to increased risk during market downturns.

Dividends

MMIBX vs. FMBIX - Dividend Comparison

MMIBX's dividend yield for the trailing twelve months is around 2.94%, while FMBIX has not paid dividends to shareholders.

	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
MMIBX MFS Municipal Income Fund	2.94%	3.81%	2.51%	2.05%	1.42%	1.45%	1.86%	2.45%	2.68%	2.67%	2.87%	2.98%
FMBIX Fidelity Municipal Bond Index Fund	0.00%	0.70%	2.60%	2.29%	1.17%	1.28%	1.59%	0.77%	0.00%	0.00%	0.00%	0.00%

Drawdowns

Drawdown Indicators

	MMIBX	FMBIX	Difference
Max Drawdown Largest peak-to-trough decline	-17.40%	—	—
Max Drawdown (1Y) Largest decline over 1 year	-5.47%	—	—
Max Drawdown (5Y) Largest decline over 5 years	-17.19%	—	—
Max Drawdown (10Y) Largest decline over 10 years	-17.19%	—	—
Current Drawdown Current decline from peak	-2.84%	—	—
Average Drawdown Average peak-to-trough decline	-2.81%	—	—
Ulcer Index Depth and duration of drawdowns from previous peaks	1.87%	—	—

Volatility

Volatility by Period

	MMIBX	FMBIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.29%	—	—
Volatility (6M) Calculated over the trailing 6-month period	1.89%	—	—
Volatility (1Y) Calculated over the trailing 1-year period	5.51%	—	—
Volatility (5Y) Calculated over the trailing 5-year period, annualized	4.36%	—	—
Volatility (10Y) Calculated over the trailing 10-year period, annualized	4.32%	—	—