CULAX vs. UGSDX

Last updated Jun 4, 2026

CULAX (Calvert Ultra-Short Duration Income Fund) and UGSDX (U.S. Global Investors U.S. Government Ultra-Short Bond Fund) are both Ultrashort Bond funds. Over the past 10 years, CULAX returned 2.47%/yr vs 1.57%/yr for UGSDX. At a 0.07 correlation, their price movements are largely independent. CULAX charges 0.72%/yr vs 1.06%/yr for UGSDX.

Performance

CULAX vs. UGSDX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Calvert Ultra-Short Duration Income Fund (CULAX) and U.S. Global Investors U.S. Government Ultra-Short Bond Fund (UGSDX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

The year-to-date returns for both stocks are quite close, with CULAX having a 1.34% return and UGSDX slightly lower at 1.32%. Over the past 10 years, CULAX has outperformed UGSDX with an annualized return of 2.47%, while UGSDX has yielded a comparatively lower 1.57% annualized return.

CULAX

• 1D: 0.00%
• 1M: 0.31%
• YTD: 1.34%
• 6M: 1.77%
• 1Y: 4.21%
• 3Y*: 5.11%
• 5Y*: 3.38%
• 10Y*: 2.47%

UGSDX

• 1D: 0.00%
• 1M: 0.25%
• YTD: 1.32%
• 6M: 1.63%
• 1Y: 3.51%
• 3Y*: 4.12%
• 5Y*: 2.30%
• 10Y*: 1.57%

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

CULAX vs. UGSDX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
CULAX Calvert Ultra-Short Duration Income Fund	1.34%	4.55%	5.69%	6.07%	-0.56%	0.43%	0.66%	3.30%	1.15%	1.27%
UGSDX U.S. Global Investors U.S. Government Ultra-Short Bond Fund	1.32%	3.93%	4.31%	4.15%	-1.66%	-0.44%	0.32%	1.49%	1.18%	1.49%

Correlation

The correlation between CULAX and UGSDX is 0.60, which is moderate. They share some common price drivers but move independently often enough to provide real diversification benefit when combined.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.60
Correlation (3Y) Calculated over the trailing 3-year period	0.12
Correlation (5Y) Calculated over the trailing 5-year period	0.11
Correlation (10Y) Calculated over the trailing 10-year period	0.11
Correlation (All Time) Calculated using the full available price history since Jan 7, 2014	0.07

Over the past year, CULAX and UGSDX have become more correlated (0.60) than their long-term average of 0.07, meaning their price movements have been converging.

Return for Risk

CULAX vs. UGSDX — Risk / Return Rank

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

CULAX

CULAX Risk / Return Rank: 98
CULAX Sharpe Ratio Rank: 94
CULAX Sortino Ratio Rank: 100
CULAX Omega Ratio Rank: 99
CULAX Calmar Ratio Rank: 99
CULAX Martin Ratio Rank: 99

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.

CULAX vs. UGSDX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Calvert Ultra-Short Duration Income Fund (CULAX) and U.S. Global Investors U.S. Government Ultra-Short Bond Fund (UGSDX). 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.

	CULAX	UGSDX	Difference
Sharpe ratio: Return per unit of total volatility	3.22	3.60	-0.38
Sortino ratio: Return per unit of downside risk	11.38	—	—
Omega ratio: Gain probability vs. loss probability	4.15	—	—
Calmar ratio: Return relative to maximum drawdown	13.98	—	—
Martin ratio: Return relative to average drawdown	56.95	—	—
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

CULAX vs. UGSDX - Sharpe Ratio Comparison

The current CULAX Sharpe Ratio is 3.22, which is comparable to the UGSDX Sharpe Ratio of 3.60. The chart below compares the historical Sharpe Ratios of CULAX and UGSDX, 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

	CULAX	UGSDX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	3.22	3.60	-0.38
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	2.53	1.29	+1.24
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	1.75	1.03	+0.71
Sharpe Ratio (All Time) Calculated using the full available price history	2.07	0.76	+1.31

Drawdowns

CULAX vs. UGSDX - Drawdown Comparison

The maximum CULAX drawdown since its inception was -7.40%, which is greater than UGSDX's maximum drawdown of -2.83%. Use the drawdown chart below to compare losses from any high point for CULAX and UGSDX.

Drawdown Indicators

	CULAX	UGSDX	Difference
Max Drawdown Largest peak-to-trough decline	-7.40%	-2.83%	-4.57%
Max Drawdown (1Y) Largest decline over 1 year	-0.30%	0.00%	-0.30%
Max Drawdown (3Y) Largest decline over 3 years	-0.30%	-0.51%	+0.21%
Max Drawdown (5Y) Largest decline over 5 years	-2.19%	-2.83%	+0.64%
Max Drawdown (10Y) Largest decline over 10 years	-7.40%	-2.83%	-4.57%
Current Drawdown Current decline from peak	0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-0.21%	-0.30%	+0.09%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.07%	0.00%	+0.07%

Volatility

CULAX vs. UGSDX - Volatility Comparison

Calvert Ultra-Short Duration Income Fund (CULAX) has a higher volatility of 0.31% compared to U.S. Global Investors U.S. Government Ultra-Short Bond Fund (UGSDX) at 0.25%. This indicates that CULAX's price experiences larger fluctuations and is considered to be riskier than UGSDX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	CULAX	UGSDX	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.31%	0.25%	+0.06%
Volatility (6M) Calculated over the trailing 6-month period	0.84%	0.65%	+0.19%
Volatility (1Y) Calculated over the trailing 1-year period	1.32%	0.98%	+0.34%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	1.35%	1.79%	-0.44%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	1.42%	1.52%	-0.10%

CULAX vs. UGSDX - Expense Ratio Comparison

CULAX has a 0.72% expense ratio, which is lower than UGSDX's 1.06% expense ratio.

Dividends

CULAX vs. UGSDX - Dividend Comparison

CULAX's dividend yield for the trailing twelve months is around 3.91%, more than UGSDX's 3.45% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
CULAX Calvert Ultra-Short Duration Income Fund	3.91%	4.13%	4.90%	4.52%	1.47%	0.64%	1.25%	2.44%	2.10%	1.13%	1.10%	0.66%
UGSDX U.S. Global Investors U.S. Government Ultra-Short Bond Fund	3.45%	3.85%	4.23%	3.55%	0.87%	0.06%	0.32%	1.48%	1.17%	1.48%	0.44%	0.44%

Frequently Asked Questions

Can I hold both CULAX and UGSDX in my portfolio?

CULAX and UGSDX have a correlation of 0.60, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, CULAX or UGSDX?

CULAX has higher volatility (0.31%) compared to UGSDX (0.25%). In terms of maximum drawdown, CULAX dropped -7.40% vs UGSDX's -2.83%.

Which has better risk-adjusted returns?

UGSDX currently has the higher Sharpe Ratio (3.60 vs 3.22), 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.