FMBIX vs. ATOIX

Last updated Jun 5, 2026

FMBIX (Fidelity Municipal Bond Index Fund) and ATOIX (abrdn Ultra Short Municipal Income Fund) are both Municipal Bonds funds. At a 0.23 correlation, their price movements are largely independent. FMBIX charges 0.07%/yr vs 0.44%/yr for ATOIX.

Performance

FMBIX vs. ATOIX - Performance Comparison

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

Returns By Period

FMBIX

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

ATOIX

• 1D: 0.00%
• 1M: 0.20%
• YTD: 1.01%
• 6M: 1.54%
• 1Y: 3.02%
• 3Y*: 3.08%
• 5Y*: 2.30%
• 10Y*: 1.79%

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

FMBIX vs. ATOIX - 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%
ATOIX abrdn Ultra Short Municipal Income Fund	1.01%	3.33%	3.14%	3.27%	0.87%	-0.04%	0.88%	0.62%

Correlation

The correlation between FMBIX and ATOIX is 0.23, which is low. Their price movements are largely independent, making them effective diversification partners.

	Correlation
Correlation (3Y) Calculated over the trailing 3-year period	0.19
Correlation (5Y) Calculated over the trailing 5-year period	0.22
Correlation (All Time) Calculated using the full available price history since Jul 18, 2019	0.23

Return for Risk

FMBIX vs. ATOIX — Risk / Return Rank

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

ATOIX

ATOIX Risk / Return Rank: 99
ATOIX Sharpe Ratio Rank: 96
ATOIX Sortino Ratio Rank: 100
ATOIX Omega Ratio Rank: 100
ATOIX Calmar Ratio Rank: 100
ATOIX Martin Ratio Rank: 100

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. ATOIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity Municipal Bond Index Fund (FMBIX) and abrdn Ultra Short Municipal Income Fund (ATOIX). 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	ATOIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	—	3.50	—
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	—	2.80	—
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	—	2.28	—
Sharpe Ratio (All Time) Calculated using the full available price history	—	2.47	—

Drawdowns

Drawdown Indicators

	FMBIX	ATOIX	Difference
Max Drawdown Largest peak-to-trough decline	—	-1.46%	—
Max Drawdown (1Y) Largest decline over 1 year	—	-0.10%	—
Max Drawdown (3Y) Largest decline over 3 years	—	-0.10%	—
Max Drawdown (5Y) Largest decline over 5 years	—	-0.37%	—
Max Drawdown (10Y) Largest decline over 10 years	—	-0.43%	—
Current Drawdown Current decline from peak	—	0.00%	—
Average Drawdown Average peak-to-trough decline	—	-0.06%	—
Ulcer Index Depth and duration of drawdowns from previous peaks	—	0.03%	—

Volatility

Volatility by Period

	FMBIX	ATOIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	—	0.20%	—
Volatility (6M) Calculated over the trailing 6-month period	—	0.61%	—
Volatility (1Y) Calculated over the trailing 1-year period	—	0.87%	—
Volatility (5Y) Calculated over the trailing 5-year period, annualized	—	0.83%	—
Volatility (10Y) Calculated over the trailing 10-year period, annualized	—	0.79%	—

FMBIX vs. ATOIX - Expense Ratio Comparison

FMBIX has a 0.07% expense ratio, which is lower than ATOIX's 0.44% expense ratio.

Dividends

FMBIX vs. ATOIX - Dividend Comparison

FMBIX has not paid dividends to shareholders, while ATOIX's dividend yield for the trailing twelve months is around 2.98%.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
ATOIX abrdn Ultra Short Municipal Income Fund	2.98%	3.27%	3.09%	3.02%	1.07%	0.06%	0.88%	1.39%	1.42%	2.20%	0.61%	0.52%
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%

Frequently Asked Questions

Can I hold both FMBIX and ATOIX in my portfolio?

FMBIX and ATOIX have a correlation of 0.23, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.