WBSIX vs. OBMCX

Last updated Jun 3, 2026

WBSIX (William Blair Small Cap Growth Fund) and OBMCX (Oberweis Micro Cap Fund) are both Small Cap Growth Equities funds. Over the past 10 years, WBSIX returned 14.65%/yr vs 21.28%/yr for OBMCX. Their correlation of 0.86 suggests significant overlap in exposure. WBSIX charges 1.25%/yr vs 1.48%/yr for OBMCX.

Performance

WBSIX vs. OBMCX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in William Blair Small Cap Growth Fund (WBSIX) and Oberweis Micro Cap Fund (OBMCX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, WBSIX achieves a 14.56% return, which is significantly lower than OBMCX's 41.55% return. Over the past 10 years, WBSIX has underperformed OBMCX with an annualized return of 14.65%, while OBMCX has yielded a comparatively higher 21.28% annualized return.

WBSIX

• 1D: -0.03%
• 1M: 3.44%
• YTD: 14.56%
• 6M: 16.81%
• 1Y: 31.17%
• 3Y*: 19.11%
• 5Y*: 7.93%
• 10Y*: 14.65%

OBMCX

• 1D: 0.92%
• 1M: -0.36%
• YTD: 41.55%
• 6M: 43.29%
• 1Y: 75.01%
• 3Y*: 28.53%
• 5Y*: 19.14%
• 10Y*: 21.28%

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

WBSIX vs. OBMCX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
WBSIX William Blair Small Cap Growth Fund	14.56%	3.03%	32.88%	16.38%	-21.46%	12.64%	38.87%	22.53%	-2.08%	26.81%
OBMCX Oberweis Micro Cap Fund	41.55%	14.70%	22.82%	18.87%	-10.57%	53.20%	29.91%	21.94%	-12.04%	27.90%

Correlation

The correlation between WBSIX and OBMCX is 0.82, 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	0.82
Correlation (3Y) Calculated over the trailing 3-year period	0.88
Correlation (5Y) Calculated over the trailing 5-year period	0.90
Correlation (10Y) Calculated over the trailing 10-year period	0.90
Correlation (All Time) Calculated using the full available price history since Dec 28, 1999	0.86

The correlation between WBSIX and OBMCX has been stable across timeframes, ranging from 0.82 to 0.90 - a consistent structural relationship.

Return for Risk

WBSIX vs. OBMCX — Risk / Return Rank

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

WBSIX

WBSIX Risk / Return Rank: 35
WBSIX Sharpe Ratio Rank: 31
WBSIX Sortino Ratio Rank: 31
WBSIX Omega Ratio Rank: 27
WBSIX Calmar Ratio Rank: 42
WBSIX Martin Ratio Rank: 42

OBMCX

OBMCX Risk / Return Rank: 88
OBMCX Sharpe Ratio Rank: 92
OBMCX Sortino Ratio Rank: 79
OBMCX Omega Ratio Rank: 75
OBMCX Calmar Ratio Rank: 96
OBMCX Martin Ratio Rank: 96

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.

WBSIX vs. OBMCX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for William Blair Small Cap Growth Fund (WBSIX) and Oberweis Micro Cap Fund (OBMCX). 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.

	WBSIX	OBMCX	Difference
Sharpe ratio Return per unit of total volatility	1.62	3.09	-1.47
Sortino ratio Return per unit of downside risk	2.34	3.76	-1.42
Omega ratio Gain probability vs. loss probability	1.27	1.49	-0.22
Calmar ratio Return relative to maximum drawdown	2.51	6.01	-3.50
Martin ratio Return relative to average drawdown	9.11	24.18	-15.07
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

WBSIX vs. OBMCX - Sharpe Ratio Comparison

The current WBSIX Sharpe Ratio is 1.62, which is lower than the OBMCX Sharpe Ratio of 3.09. The chart below compares the historical Sharpe Ratios of WBSIX and OBMCX, 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

	WBSIX	OBMCX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.62	3.09	-1.47
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.33	0.74	-0.40
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.64	0.83	-0.19
Sharpe Ratio (All Time) Calculated using the full available price history	0.54	0.45	+0.09

Drawdowns

WBSIX vs. OBMCX - Drawdown Comparison

The maximum WBSIX drawdown since its inception was -62.35%, smaller than the maximum OBMCX drawdown of -68.24%. Use the drawdown chart below to compare losses from any high point for WBSIX and OBMCX.

Drawdown Indicators

	WBSIX	OBMCX	Difference
Max Drawdown Largest peak-to-trough decline	-62.35%	-68.24%	+5.89%
Max Drawdown (1Y) Largest decline over 1 year	-12.75%	-12.45%	-0.30%
Max Drawdown (3Y) Largest decline over 3 years	-24.76%	-28.11%	+3.35%
Max Drawdown (5Y) Largest decline over 5 years	-38.13%	-28.11%	-10.02%
Max Drawdown (10Y) Largest decline over 10 years	-39.16%	-50.04%	+10.88%
Current Drawdown Current decline from peak	-0.59%	-2.09%	+1.50%
Average Drawdown Average peak-to-trough decline	-11.14%	-16.42%	+5.28%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.51%	3.09%	+0.42%

Volatility

WBSIX vs. OBMCX - Volatility Comparison

The current volatility for William Blair Small Cap Growth Fund (WBSIX) is 5.50%, while Oberweis Micro Cap Fund (OBMCX) has a volatility of 7.91%. This indicates that WBSIX experiences smaller price fluctuations and is considered to be less risky than OBMCX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	WBSIX	OBMCX	Difference
Volatility (1M) Calculated over the trailing 1-month period	5.50%	7.91%	-2.41%
Volatility (6M) Calculated over the trailing 6-month period	14.42%	18.48%	-4.06%
Volatility (1Y) Calculated over the trailing 1-year period	19.99%	24.79%	-4.80%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	23.85%	26.17%	-2.32%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	23.02%	25.86%	-2.84%

WBSIX vs. OBMCX - Expense Ratio Comparison

WBSIX has a 1.25% expense ratio, which is lower than OBMCX's 1.48% expense ratio.

Dividends

WBSIX vs. OBMCX - Dividend Comparison

WBSIX's dividend yield for the trailing twelve months is around 6.54%, more than OBMCX's 1.00% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
OBMCX Oberweis Micro Cap Fund	1.00%	1.41%	2.53%	0.00%	1.37%	24.35%	0.00%	0.00%	19.67%	11.76%	0.05%	3.07%
WBSIX William Blair Small Cap Growth Fund	6.54%	7.49%	20.14%	1.53%	3.55%	17.85%	9.73%	2.07%	12.60%	16.89%	5.42%	8.25%

Frequently Asked Questions

Can I hold both WBSIX and OBMCX in my portfolio?

WBSIX and OBMCX have a correlation of 0.82, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, WBSIX or OBMCX?

OBMCX has higher volatility (7.91%) compared to WBSIX (5.50%). In terms of maximum drawdown, WBSIX dropped -62.35% vs OBMCX's -68.24%.

Which has better risk-adjusted returns?

OBMCX currently has the higher Sharpe Ratio (3.09 vs 1.62), 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.