OBSOX vs. VSGIX

Last updated Jun 4, 2026

OBSOX (Oberweis Small-Cap Opportunities Fund) and VSGIX (Vanguard Small-Cap Growth Index Fund Institutional Shares) are both Small Cap Growth Equities funds. Over the past 10 years, OBSOX returned 19.01%/yr vs 11.86%/yr for VSGIX. Their correlation of 0.92 suggests significant overlap in exposure. OBSOX charges 1.25%/yr vs 0.06%/yr for VSGIX.

Performance

OBSOX vs. VSGIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Oberweis Small-Cap Opportunities Fund (OBSOX) and Vanguard Small-Cap Growth Index Fund Institutional Shares (VSGIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, OBSOX achieves a 36.53% return, which is significantly higher than VSGIX's 18.74% return. Over the past 10 years, OBSOX has outperformed VSGIX with an annualized return of 19.01%, while VSGIX has yielded a comparatively lower 11.86% annualized return.

OBSOX

• 1D: 2.92%
• 1M: 8.39%
• YTD: 36.53%
• 6M: 35.36%
• 1Y: 60.95%
• 3Y*: 24.06%
• 5Y*: 17.06%
• 10Y*: 19.01%

VSGIX

• 1D: 0.72%
• 1M: 6.06%
• YTD: 18.74%
• 6M: 18.16%
• 1Y: 34.12%
• 3Y*: 18.14%
• 5Y*: 6.12%
• 10Y*: 11.86%

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

OBSOX vs. VSGIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
OBSOX Oberweis Small-Cap Opportunities Fund	36.53%	14.28%	16.13%	15.81%	-11.17%	43.39%	32.52%	25.06%	-7.05%	25.55%
VSGIX Vanguard Small-Cap Growth Index Fund Institutional Shares	18.74%	8.44%	14.95%	23.07%	-28.39%	5.70%	35.29%	32.77%	-5.70%	21.94%

Correlation

The correlation between OBSOX and VSGIX is 0.86, 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	0.86
Correlation (3Y) Calculated over the trailing 3-year period	0.91
Correlation (5Y) Calculated over the trailing 5-year period	0.92
Correlation (10Y) Calculated over the trailing 10-year period	0.93
Correlation (All Time) Calculated using the full available price history since May 25, 2000	0.92

The correlation between OBSOX and VSGIX has been stable across timeframes, ranging from 0.86 to 0.93 - a consistent structural relationship.

Return for Risk

OBSOX vs. VSGIX — Risk / Return Rank

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

OBSOX

OBSOX Risk / Return Rank: 75
OBSOX Sharpe Ratio Rank: 75
OBSOX Sortino Ratio Rank: 57
OBSOX Omega Ratio Rank: 55
OBSOX Calmar Ratio Rank: 94
OBSOX Martin Ratio Rank: 94

VSGIX

VSGIX Risk / Return Rank: 48
VSGIX Sharpe Ratio Rank: 41
VSGIX Sortino Ratio Rank: 38
VSGIX Omega Ratio Rank: 35
VSGIX Calmar Ratio Rank: 68
VSGIX Martin Ratio Rank: 61

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.

OBSOX vs. VSGIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Oberweis Small-Cap Opportunities Fund (OBSOX) and Vanguard Small-Cap Growth Index Fund Institutional Shares (VSGIX). 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.

	OBSOX	VSGIX	Difference
Sharpe ratio: Return per unit of total volatility	2.51	1.86	+0.66
Sortino ratio: Return per unit of downside risk	3.18	2.56	+0.62
Omega ratio: Gain probability vs. loss probability	1.41	1.31	+0.10
Calmar ratio: Return relative to maximum drawdown	5.64	3.17	+2.46
Martin ratio: Return relative to average drawdown	20.82	12.10	+8.72
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

OBSOX vs. VSGIX - Sharpe Ratio Comparison

The current OBSOX Sharpe Ratio is 2.51, which is higher than the VSGIX Sharpe Ratio of 1.86. The chart below compares the historical Sharpe Ratios of OBSOX and VSGIX, 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

	OBSOX	VSGIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.51	1.86	+0.66
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.68	0.26	+0.42
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.77	0.52	+0.25
Sharpe Ratio (All Time) Calculated using the full available price history	0.33	0.41	-0.07

Drawdowns

OBSOX vs. VSGIX - Drawdown Comparison

The maximum OBSOX drawdown since its inception was -80.52%, which is greater than VSGIX's maximum drawdown of -58.66%. Use the drawdown chart below to compare losses from any high point for OBSOX and VSGIX.

Drawdown Indicators

	OBSOX	VSGIX	Difference
Max Drawdown Largest peak-to-trough decline	-80.52%	-58.66%	-21.86%
Max Drawdown (1Y) Largest decline over 1 year	-11.40%	-11.38%	-0.02%
Max Drawdown (3Y) Largest decline over 3 years	-27.74%	-27.47%	-0.27%
Max Drawdown (5Y) Largest decline over 5 years	-28.65%	-38.36%	+9.71%
Max Drawdown (10Y) Largest decline over 10 years	-42.79%	-38.70%	-4.09%
Current Drawdown Current decline from peak	0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-30.55%	-11.34%	-19.21%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.07%	2.98%	+0.09%

Volatility

OBSOX vs. VSGIX - Volatility Comparison

Oberweis Small-Cap Opportunities Fund (OBSOX) has a higher volatility of 8.92% compared to Vanguard Small-Cap Growth Index Fund Institutional Shares (VSGIX) at 5.28%. This indicates that OBSOX's price experiences larger fluctuations and is considered to be riskier than VSGIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	OBSOX	VSGIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	8.92%	5.28%	+3.64%
Volatility (6M) Calculated over the trailing 6-month period	20.40%	14.85%	+5.55%
Volatility (1Y) Calculated over the trailing 1-year period	25.56%	19.45%	+6.11%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	25.07%	23.56%	+1.51%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	24.77%	22.98%	+1.79%

OBSOX vs. VSGIX - Expense Ratio Comparison

OBSOX has a 1.25% expense ratio, which is higher than VSGIX's 0.06% expense ratio.

Dividends

OBSOX vs. VSGIX - Dividend Comparison

OBSOX has not paid dividends to shareholders, while VSGIX's dividend yield for the trailing twelve months is around 0.45%.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
OBSOX Oberweis Small-Cap Opportunities Fund	0.00%	0.00%	0.80%	0.00%	0.17%	21.88%	4.05%	3.04%	28.22%	6.36%	4.24%	11.91%
VSGIX Vanguard Small-Cap Growth Index Fund Institutional Shares	0.45%	0.55%	0.55%	0.68%	0.56%	0.37%	0.45%	0.58%	0.80%	0.82%	1.09%	0.98%

Frequently Asked Questions

Can I hold both OBSOX and VSGIX in my portfolio?

OBSOX and VSGIX have a correlation of 0.86, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, OBSOX or VSGIX?

OBSOX has higher volatility (8.92%) compared to VSGIX (5.28%). In terms of maximum drawdown, OBSOX dropped -80.52% vs VSGIX's -58.66%.

Which has better risk-adjusted returns?

OBSOX currently has the higher Sharpe Ratio (2.51 vs 1.86), 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.