OWMBX vs. ATOIX

Last updated Jun 3, 2026

OWMBX (Old Westbury Municipal Bond Fund) and ATOIX (abrdn Ultra Short Municipal Income Fund) are both Municipal Bonds funds. Over the past 10 years, OWMBX returned 1.41%/yr vs 1.79%/yr for ATOIX. At a 0.22 correlation, their price movements are largely independent. OWMBX charges 0.57%/yr vs 0.44%/yr for ATOIX.

Performance

OWMBX vs. ATOIX - Performance Comparison

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

Returns By Period

In the year-to-date period, OWMBX achieves a 0.28% return, which is significantly lower than ATOIX's 1.01% return. Over the past 10 years, OWMBX has underperformed ATOIX with an annualized return of 1.41%, while ATOIX has yielded a comparatively higher 1.79% annualized return.

OWMBX

• 1D: 0.00%
• 1M: 0.17%
• YTD: 0.28%
• 6M: 0.67%
• 1Y: 4.37%
• 3Y*: 2.71%
• 5Y*: 0.62%
• 10Y*: 1.41%

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)

OWMBX vs. ATOIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
OWMBX Old Westbury Municipal Bond Fund	0.28%	4.29%	0.43%	4.03%	-5.39%	-0.63%	5.01%	5.58%	0.87%	2.22%
ATOIX abrdn Ultra Short Municipal Income Fund	1.01%	3.33%	3.14%	3.27%	0.87%	-0.04%	0.88%	1.40%	1.54%	2.24%

Correlation

The correlation between OWMBX and ATOIX is 0.15, which is low. Their price movements are largely independent, making them effective diversification partners.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.15
Correlation (3Y) Calculated over the trailing 3-year period	0.13
Correlation (5Y) Calculated over the trailing 5-year period	0.16
Correlation (10Y) Calculated over the trailing 10-year period	0.14
Correlation (All Time) Calculated using the full available price history since Dec 20, 2002	0.22

Return for Risk

OWMBX vs. ATOIX — Risk / Return Rank

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

OWMBX

OWMBX Risk / Return Rank: 62
OWMBX Sharpe Ratio Rank: 76
OWMBX Sortino Ratio Rank: 78
OWMBX Omega Ratio Rank: 92
OWMBX Calmar Ratio Rank: 36
OWMBX Martin Ratio Rank: 29

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.

OWMBX vs. ATOIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Old Westbury Municipal Bond Fund (OWMBX) 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.

	OWMBX	ATOIX	Difference
Sharpe ratio Return per unit of total volatility	2.53	3.50	-0.97
Sortino ratio Return per unit of downside risk	3.72	17.32	-13.61
Omega ratio Gain probability vs. loss probability	1.68	10.98	-9.30
Calmar ratio Return relative to maximum drawdown	2.28	32.90	-30.62
Martin ratio Return relative to average drawdown	6.97	97.00	-90.02
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

OWMBX vs. ATOIX - Sharpe Ratio Comparison

The current OWMBX Sharpe Ratio is 2.53, which is comparable to the ATOIX Sharpe Ratio of 3.50. The chart below compares the historical Sharpe Ratios of OWMBX and ATOIX, 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

	OWMBX	ATOIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.53	3.50	-0.97
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.20	2.80	-2.59
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.47	2.28	-1.81
Sharpe Ratio (All Time) Calculated using the full available price history	1.05	2.47	-1.42

Drawdowns

OWMBX vs. ATOIX - Drawdown Comparison

The maximum OWMBX drawdown since its inception was -9.54%, which is greater than ATOIX's maximum drawdown of -1.46%. Use the drawdown chart below to compare losses from any high point for OWMBX and ATOIX.

Drawdown Indicators

	OWMBX	ATOIX	Difference
Max Drawdown Largest peak-to-trough decline	-9.54%	-1.46%	-8.08%
Max Drawdown (1Y) Largest decline over 1 year	-2.45%	-0.10%	-2.35%
Max Drawdown (3Y) Largest decline over 3 years	-3.81%	-0.10%	-3.71%
Max Drawdown (5Y) Largest decline over 5 years	-9.37%	-0.37%	-9.00%
Max Drawdown (10Y) Largest decline over 10 years	-9.44%	-0.43%	-9.01%
Current Drawdown Current decline from peak	-1.33%	0.00%	-1.33%
Average Drawdown Average peak-to-trough decline	-1.64%	-0.06%	-1.58%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.80%	0.03%	+0.77%

Volatility

OWMBX vs. ATOIX - Volatility Comparison

Old Westbury Municipal Bond Fund (OWMBX) has a higher volatility of 0.64% compared to abrdn Ultra Short Municipal Income Fund (ATOIX) at 0.20%. This indicates that OWMBX's price experiences larger fluctuations and is considered to be riskier than ATOIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	OWMBX	ATOIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.64%	0.20%	+0.44%
Volatility (6M) Calculated over the trailing 6-month period	1.44%	0.65%	+0.79%
Volatility (1Y) Calculated over the trailing 1-year period	1.92%	0.87%	+1.05%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	3.11%	0.83%	+2.28%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	3.04%	0.79%	+2.25%

OWMBX vs. ATOIX - Expense Ratio Comparison

OWMBX has a 0.57% expense ratio, which is higher than ATOIX's 0.44% expense ratio.

Dividends

OWMBX vs. ATOIX - Dividend Comparison

OWMBX's dividend yield for the trailing twelve months is around 2.61%, less than ATOIX's 2.98% yield.

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%
OWMBX Old Westbury Municipal Bond Fund	2.61%	2.61%	2.54%	2.01%	1.15%	2.06%	2.55%	1.68%	1.45%	1.18%	1.61%	1.40%

Frequently Asked Questions

Can I hold both OWMBX and ATOIX in my portfolio?

OWMBX and ATOIX have a correlation of 0.15, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, OWMBX or ATOIX?

OWMBX has higher volatility (0.64%) compared to ATOIX (0.20%). In terms of maximum drawdown, OWMBX dropped -9.54% vs ATOIX's -1.46%.

Which has better risk-adjusted returns?

ATOIX currently has the higher Sharpe Ratio (3.50 vs 2.53), 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.