OBIOX vs. VFSAX

Last updated Jun 4, 2026

OBIOX (Oberweis International Opportunities Fund) and VFSAX (Vanguard FTSE All-World ex-US Small-Cap Index Fund Admiral Shares) are both Foreign Small & Mid Cap Equities funds. Over the past 5 years, OBIOX returned -0.54%/yr vs 6.13%/yr for VFSAX. Their correlation of 0.84 suggests significant overlap in exposure. OBIOX charges 1.60%/yr vs 0.16%/yr for VFSAX.

Performance

OBIOX vs. VFSAX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Oberweis International Opportunities Fund (OBIOX) and Vanguard FTSE All-World ex-US Small-Cap Index Fund Admiral Shares (VFSAX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, OBIOX achieves a 9.62% return, which is significantly lower than VFSAX's 11.72% return.

OBIOX

• 1D: 0.04%
• 1M: 2.74%
• YTD: 9.62%
• 6M: 11.56%
• 1Y: 19.19%
• 3Y*: 16.80%
• 5Y*: -0.54%
• 10Y*: 7.04%

VFSAX

• 1D: 0.05%
• 1M: 1.80%
• YTD: 11.72%
• 6M: 14.53%
• 1Y: 28.52%
• 3Y*: 17.12%
• 5Y*: 6.13%
• 10Y*: —

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

OBIOX vs. VFSAX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019
OBIOX Oberweis International Opportunities Fund	9.62%	30.71%	7.54%	4.90%	-37.06%	1.41%	62.87%	10.51%
VFSAX Vanguard FTSE All-World ex-US Small-Cap Index Fund Admiral Shares	11.72%	29.89%	2.58%	15.13%	-21.30%	12.68%	11.90%	13.47%

Correlation

The correlation between OBIOX and VFSAX is 0.84, indicating a strong positive relationship between their price movements. Combining them offers limited diversification - they tend to fall together during downturns.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.84
Correlation (3Y) Calculated over the trailing 3-year period	0.83
Correlation (5Y) Calculated over the trailing 5-year period	0.87
Correlation (All Time) Calculated using the full available price history since Feb 8, 2019	0.84

The correlation between OBIOX and VFSAX has been stable across timeframes, ranging from 0.83 to 0.87 - a consistent structural relationship.

Return for Risk

OBIOX vs. VFSAX — Risk / Return Rank

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

OBIOX

OBIOX Risk / Return Rank: 14
OBIOX Sharpe Ratio Rank: 15
OBIOX Sortino Ratio Rank: 15
OBIOX Omega Ratio Rank: 15
OBIOX Calmar Ratio Rank: 12
OBIOX Martin Ratio Rank: 14

VFSAX

VFSAX Risk / Return Rank: 47
VFSAX Sharpe Ratio Rank: 51
VFSAX Sortino Ratio Rank: 47
VFSAX Omega Ratio Rank: 50
VFSAX Calmar Ratio Rank: 42
VFSAX Martin Ratio Rank: 45

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.

OBIOX vs. VFSAX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Oberweis International Opportunities Fund (OBIOX) and Vanguard FTSE All-World ex-US Small-Cap Index Fund Admiral Shares (VFSAX). 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.

	OBIOX	VFSAX	Difference
Sharpe ratio: Return per unit of total volatility	1.09	2.11	-1.02
Sortino ratio: Return per unit of downside risk	1.60	2.88	-1.28
Omega ratio: Gain probability vs. loss probability	1.20	1.39	-0.19
Calmar ratio: Return relative to maximum drawdown	1.16	2.45	-1.30
Martin ratio: Return relative to average drawdown	4.11	9.44	-5.33
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

OBIOX vs. VFSAX - Sharpe Ratio Comparison

The current OBIOX Sharpe Ratio is 1.09, which is lower than the VFSAX Sharpe Ratio of 2.11. The chart below compares the historical Sharpe Ratios of OBIOX and VFSAX, 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

	OBIOX	VFSAX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.09	2.11	-1.02
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	-0.03	0.41	-0.44
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.36	—	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.38	0.55	-0.18

Drawdowns

OBIOX vs. VFSAX - Drawdown Comparison

The maximum OBIOX drawdown since its inception was -71.17%, which is greater than VFSAX's maximum drawdown of -39.86%. Use the drawdown chart below to compare losses from any high point for OBIOX and VFSAX.

Drawdown Indicators

	OBIOX	VFSAX	Difference
Max Drawdown Largest peak-to-trough decline	-71.17%	-39.86%	-31.31%
Max Drawdown (1Y) Largest decline over 1 year	-15.64%	-11.48%	-4.16%
Max Drawdown (3Y) Largest decline over 3 years	-17.48%	-14.73%	-2.75%
Max Drawdown (5Y) Largest decline over 5 years	-51.47%	-33.81%	-17.66%
Max Drawdown (10Y) Largest decline over 10 years	-51.47%	—	—
Current Drawdown Current decline from peak	-10.64%	-1.08%	-9.56%
Average Drawdown Average peak-to-trough decline	-21.45%	-9.26%	-12.19%
Ulcer Index Depth and duration of drawdowns from previous peaks	4.40%	2.98%	+1.42%

Volatility

OBIOX vs. VFSAX - Volatility Comparison

Oberweis International Opportunities Fund (OBIOX) has a higher volatility of 4.98% compared to Vanguard FTSE All-World ex-US Small-Cap Index Fund Admiral Shares (VFSAX) at 4.31%. This indicates that OBIOX's price experiences larger fluctuations and is considered to be riskier than VFSAX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	OBIOX	VFSAX	Difference
Volatility (1M) Calculated over the trailing 1-month period	4.98%	4.31%	+0.67%
Volatility (6M) Calculated over the trailing 6-month period	14.09%	11.18%	+2.91%
Volatility (1Y) Calculated over the trailing 1-year period	16.67%	13.39%	+3.28%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	19.77%	15.04%	+4.73%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	19.82%	17.03%	+2.79%

OBIOX vs. VFSAX - Expense Ratio Comparison

OBIOX has a 1.60% expense ratio, which is higher than VFSAX's 0.16% expense ratio.

Dividends

OBIOX vs. VFSAX - Dividend Comparison

OBIOX's dividend yield for the trailing twelve months is around 1.00%, less than VFSAX's 2.96% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
OBIOX Oberweis International Opportunities Fund	1.00%	1.10%	1.27%	0.43%	0.00%	20.69%	0.40%	1.23%	17.03%	11.47%	0.07%	0.19%
VFSAX Vanguard FTSE All-World ex-US Small-Cap Index Fund Admiral Shares	2.96%	3.31%	3.36%	3.06%	2.22%	2.67%	1.85%	3.19%	0.00%	0.00%	0.00%	0.00%

Frequently Asked Questions

Can I hold both OBIOX and VFSAX in my portfolio?

OBIOX and VFSAX have a correlation of 0.84, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, OBIOX or VFSAX?

OBIOX has higher volatility (4.98%) compared to VFSAX (4.31%). In terms of maximum drawdown, OBIOX dropped -71.17% vs VFSAX's -39.86%.

Which has better risk-adjusted returns?

VFSAX currently has the higher Sharpe Ratio (2.11 vs 1.09), 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.