FMBIX vs. MUB

Last updated Jun 3, 2026

FMBIX (Fidelity Municipal Bond Index Fund) and MUB (iShares National AMT-Free Muni Bond ETF) are both Municipal Bonds funds. A 0.62 correlation means they provide meaningful diversification when combined. Both charge a 0.07% expense ratio.

Performance

FMBIX vs. MUB - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Fidelity Municipal Bond Index Fund (FMBIX) and iShares National AMT-Free Muni Bond ETF (MUB). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

FMBIX

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

MUB

• 1D: 0.15%
• 1M: 0.53%
• YTD: 1.32%
• 6M: 1.88%
• 1Y: 7.06%
• 3Y*: 3.46%
• 5Y*: 0.91%
• 10Y*: 2.00%

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

FMBIX vs. MUB - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019
FMBIX Fidelity Municipal Bond Index Fund	0.00%	0.60%	1.32%	5.89%	-10.00%	1.14%	3.10%	1.48%
MUB iShares National AMT-Free Muni Bond ETF	1.32%	3.78%	1.26%	5.56%	-7.34%	1.02%	5.12%	1.62%

Correlation

The correlation between FMBIX and MUB is 0.62, which is moderate. They share some common price drivers but move independently often enough to provide real diversification benefit when combined.

	Correlation
Correlation (3Y) Calculated over the trailing 3-year period	0.59
Correlation (5Y) Calculated over the trailing 5-year period	0.63
Correlation (All Time) Calculated using the full available price history since Jul 18, 2019	0.62

The correlation between FMBIX and MUB has been stable across timeframes, ranging from 0.59 to 0.63 - a consistent structural relationship.

Return for Risk

FMBIX vs. MUB — Risk / Return Rank

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

MUB

MUB Risk / Return Rank: 67
MUB Sharpe Ratio Rank: 74
MUB Sortino Ratio Rank: 78
MUB Omega Ratio Rank: 84
MUB Calmar Ratio Rank: 48
MUB Martin Ratio Rank: 50

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.

FMBIX vs. MUB - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity Municipal Bond Index Fund (FMBIX) and iShares National AMT-Free Muni Bond ETF (MUB). 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.

Risk / return metrics aren't available yet — we need at least 12 months of trading data to calculate them.

Sharpe Ratios by Period

	FMBIX	MUB	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	—	2.43	—
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	—	0.23	—
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	—

Drawdowns

Drawdown Indicators

	FMBIX	MUB	Difference
Max Drawdown Largest peak-to-trough decline	—	-13.68%	—
Max Drawdown (1Y) Largest decline over 1 year	—	-2.79%	—
Max Drawdown (3Y) Largest decline over 3 years	—	-5.34%	—
Max Drawdown (5Y) Largest decline over 5 years	—	-11.88%	—
Max Drawdown (10Y) Largest decline over 10 years	—	-13.68%	—
Current Drawdown Current decline from peak	—	-0.62%	—
Average Drawdown Average peak-to-trough decline	—	-2.23%	—
Ulcer Index Depth and duration of drawdowns from previous peaks	—	0.79%	—

Volatility

Volatility by Period

	FMBIX	MUB	Difference
Volatility (1M) Calculated over the trailing 1-month period	—	0.98%	—
Volatility (6M) Calculated over the trailing 6-month period	—	2.23%	—
Volatility (1Y) Calculated over the trailing 1-year period	—	2.93%	—
Volatility (5Y) Calculated over the trailing 5-year period, annualized	—	4.06%	—
Volatility (10Y) Calculated over the trailing 10-year period, annualized	—	4.92%	—

FMBIX vs. MUB - Expense Ratio Comparison

Both FMBIX and MUB have an expense ratio of 0.07%, making them cost-effective options compared to the broader market, where average expense ratios typically range from 0.3% to 0.9%.

Dividends

FMBIX vs. MUB - Dividend Comparison

FMBIX has not paid dividends to shareholders, while MUB's dividend yield for the trailing twelve months is around 3.17%.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
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%
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

Can I hold both FMBIX and MUB in my portfolio?

FMBIX and MUB have a correlation of 0.62, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.