OBSOX vs. OAKMX

Last updated Jun 3, 2026

OBSOX (Oberweis Small-Cap Opportunities Fund) and OAKMX (Oakmark Fund Investor Class) are both mutual funds - OBSOX is a Small Cap Growth Equities fund managed by Oberweis, while OAKMX is a Large Cap Value Equities fund managed by Oakmark. Over the past 10 years, OBSOX returned 18.67%/yr vs 13.49%/yr for OAKMX. A 0.72 correlation means they provide meaningful diversification when combined. OBSOX charges 1.25%/yr vs 0.91%/yr for OAKMX.

Performance

OBSOX vs. OAKMX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Oberweis Small-Cap Opportunities Fund (OBSOX) and Oakmark Fund Investor Class (OAKMX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, OBSOX achieves a 32.65% return, which is significantly higher than OAKMX's -0.14% return. Over the past 10 years, OBSOX has outperformed OAKMX with an annualized return of 18.67%, while OAKMX has yielded a comparatively lower 13.49% annualized return.

OBSOX

• 1D: 1.34%
• 1M: 5.11%
• YTD: 32.65%
• 6M: 33.47%
• 1Y: 58.95%
• 3Y*: 22.87%
• 5Y*: 16.20%
• 10Y*: 18.67%

OAKMX

• 1D: 0.83%
• 1M: 0.02%
• YTD: -0.14%
• 6M: 4.31%
• 1Y: 13.16%
• 3Y*: 15.33%
• 5Y*: 9.65%
• 10Y*: 13.49%

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

OBSOX vs. OAKMX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
OBSOX Oberweis Small-Cap Opportunities Fund	32.65%	14.28%	16.13%	15.81%	-11.17%	43.39%	32.52%	25.06%	-7.05%	25.55%
OAKMX Oakmark Fund Investor Class	-0.14%	14.13%	16.02%	30.92%	-13.38%	34.85%	12.90%	27.14%	-12.76%	21.12%

Correlation

The correlation between OBSOX and OAKMX is 0.47, which is low. Their price movements are largely independent, making them effective diversification partners.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.47
Correlation (3Y) Calculated over the trailing 3-year period	0.63
Correlation (5Y) Calculated over the trailing 5-year period	0.74
Correlation (10Y) Calculated over the trailing 10-year period	0.75
Correlation (All Time) Calculated using the full available price history since Sep 17, 1996	0.72

Over the past year, the correlation between OBSOX and OAKMX has dropped to 0.47 - well below their long-term average of 0.72, suggesting their price drivers have been diverging.

Return for Risk

OBSOX vs. OAKMX — Risk / Return Rank

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

OBSOX

OBSOX Risk / Return Rank: 71
OBSOX Sharpe Ratio Rank: 67
OBSOX Sortino Ratio Rank: 52
OBSOX Omega Ratio Rank: 51
OBSOX Calmar Ratio Rank: 93
OBSOX Martin Ratio Rank: 92

OAKMX

OAKMX Risk / Return Rank: 15
OAKMX Sharpe Ratio Rank: 12
OAKMX Sortino Ratio Rank: 13
OAKMX Omega Ratio Rank: 12
OAKMX Calmar Ratio Rank: 23
OAKMX Martin Ratio Rank: 16

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. OAKMX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Oberweis Small-Cap Opportunities Fund (OBSOX) and Oakmark Fund Investor Class (OAKMX). 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	OAKMX	Difference
Sharpe ratio Return per unit of total volatility	2.39	0.99	+1.41
Sortino ratio Return per unit of downside risk	3.05	1.49	+1.56
Omega ratio Gain probability vs. loss probability	1.39	1.18	+0.21
Calmar ratio Return relative to maximum drawdown	5.22	1.84	+3.39
Martin ratio Return relative to average drawdown	19.37	4.73	+14.63
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. OAKMX - Sharpe Ratio Comparison

The current OBSOX Sharpe Ratio is 2.39, which is higher than the OAKMX Sharpe Ratio of 0.99. The chart below compares the historical Sharpe Ratios of OBSOX and OAKMX, 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	OAKMX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.39	0.99	+1.41
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.65	0.53	+0.12
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.76	0.66	+0.09
Sharpe Ratio (All Time) Calculated using the full available price history	0.33	0.71	-0.38

Drawdowns

OBSOX vs. OAKMX - Drawdown Comparison

The maximum OBSOX drawdown since its inception was -80.52%, which is greater than OAKMX's maximum drawdown of -56.19%. Use the drawdown chart below to compare losses from any high point for OBSOX and OAKMX.

Drawdown Indicators

	OBSOX	OAKMX	Difference
Max Drawdown Largest peak-to-trough decline	-80.52%	-56.19%	-24.33%
Max Drawdown (1Y) Largest decline over 1 year	-11.40%	-6.98%	-4.42%
Max Drawdown (3Y) Largest decline over 3 years	-27.74%	-17.05%	-10.69%
Max Drawdown (5Y) Largest decline over 5 years	-28.65%	-23.68%	-4.97%
Max Drawdown (10Y) Largest decline over 10 years	-42.79%	-41.43%	-1.36%
Current Drawdown Current decline from peak	-0.62%	-2.70%	+2.08%
Average Drawdown Average peak-to-trough decline	-30.55%	-6.39%	-24.16%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.07%	2.71%	+0.36%

Volatility

OBSOX vs. OAKMX - Volatility Comparison

Oberweis Small-Cap Opportunities Fund (OBSOX) has a higher volatility of 8.66% compared to Oakmark Fund Investor Class (OAKMX) at 2.82%. This indicates that OBSOX's price experiences larger fluctuations and is considered to be riskier than OAKMX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	OBSOX	OAKMX	Difference
Volatility (1M) Calculated over the trailing 1-month period	8.66%	2.82%	+5.84%
Volatility (6M) Calculated over the trailing 6-month period	20.24%	9.31%	+10.93%
Volatility (1Y) Calculated over the trailing 1-year period	25.47%	13.00%	+12.47%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	25.04%	18.28%	+6.76%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	24.76%	20.40%	+4.36%

OBSOX vs. OAKMX - Expense Ratio Comparison

OBSOX has a 1.25% expense ratio, which is higher than OAKMX's 0.91% expense ratio.

Dividends

OBSOX vs. OAKMX - Dividend Comparison

OBSOX has not paid dividends to shareholders, while OAKMX's dividend yield for the trailing twelve months is around 0.92%.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
OAKMX Oakmark Fund Investor Class	0.92%	0.92%	1.12%	1.02%	0.92%	1.94%	0.17%	8.33%	8.13%	4.06%	2.58%	1.43%
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%

Frequently Asked Questions

Can I hold both OBSOX and OAKMX in my portfolio?

OBSOX and OAKMX have a correlation of 0.47, 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 OAKMX?

OBSOX has higher volatility (8.66%) compared to OAKMX (2.82%). In terms of maximum drawdown, OBSOX dropped -80.52% vs OAKMX's -56.19%.

Which has better risk-adjusted returns?

OBSOX currently has the higher Sharpe Ratio (2.39 vs 0.99), 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.