NESGX vs. WBSIX

Last updated Jun 3, 2026

NESGX (Needham Small Cap Growth Fund) and WBSIX (William Blair Small Cap Growth Fund) are both Small Cap Growth Equities funds. Over the past 10 years, NESGX returned 19.69%/yr vs 14.65%/yr for WBSIX. Their correlation of 0.85 suggests significant overlap in exposure. NESGX charges 1.85%/yr vs 1.25%/yr for WBSIX.

Performance

NESGX vs. WBSIX - Performance Comparison

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

Returns By Period

In the year-to-date period, NESGX achieves a 74.77% return, which is significantly higher than WBSIX's 14.56% return. Over the past 10 years, NESGX has outperformed WBSIX with an annualized return of 19.69%, while WBSIX has yielded a comparatively lower 14.65% annualized return.

NESGX

• 1D: 1.48%
• 1M: 18.07%
• YTD: 74.77%
• 6M: 77.64%
• 1Y: 122.24%
• 3Y*: 31.38%
• 5Y*: 9.34%
• 10Y*: 19.69%

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%

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

NESGX vs. WBSIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
NESGX Needham Small Cap Growth Fund	74.77%	10.50%	12.76%	5.68%	-30.21%	10.59%	71.90%	54.42%	-5.43%	11.96%
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%

Correlation

The correlation between NESGX and WBSIX is 0.83, 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	0.83
Correlation (3Y) Calculated over the trailing 3-year period	0.85
Correlation (5Y) Calculated over the trailing 5-year period	0.87
Correlation (10Y) Calculated over the trailing 10-year period	0.84
Correlation (All Time) Calculated using the full available price history since May 24, 2002	0.85

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

Return for Risk

NESGX vs. WBSIX — Risk / Return Rank

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

NESGX

NESGX Risk / Return Rank: 94
NESGX Sharpe Ratio Rank: 98
NESGX Sortino Ratio Rank: 91
NESGX Omega Ratio Rank: 86
NESGX Calmar Ratio Rank: 97
NESGX Martin Ratio Rank: 97

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

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.

NESGX vs. WBSIX - Risk-Adjusted Trends Comparison

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

	NESGX	WBSIX	Difference
Sharpe ratio Return per unit of total volatility	4.11	1.62	+2.50
Sortino ratio Return per unit of downside risk	4.49	2.34	+2.15
Omega ratio Gain probability vs. loss probability	1.58	1.27	+0.31
Calmar ratio Return relative to maximum drawdown	6.96	2.51	+4.45
Martin ratio Return relative to average drawdown	28.90	9.11	+19.79
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

NESGX vs. WBSIX - Sharpe Ratio Comparison

The current NESGX Sharpe Ratio is 4.11, which is higher than the WBSIX Sharpe Ratio of 1.62. The chart below compares the historical Sharpe Ratios of NESGX and WBSIX, 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

	NESGX	WBSIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	4.11	1.62	+2.50
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.32	0.33	-0.01
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.77	0.64	+0.13
Sharpe Ratio (All Time) Calculated using the full available price history	0.61	0.54	+0.07

Drawdowns

NESGX vs. WBSIX - Drawdown Comparison

The maximum NESGX drawdown since its inception was -50.29%, smaller than the maximum WBSIX drawdown of -62.35%. Use the drawdown chart below to compare losses from any high point for NESGX and WBSIX.

Drawdown Indicators

	NESGX	WBSIX	Difference
Max Drawdown Largest peak-to-trough decline	-50.29%	-62.35%	+12.06%
Max Drawdown (1Y) Largest decline over 1 year	-17.16%	-12.75%	-4.41%
Max Drawdown (3Y) Largest decline over 3 years	-35.27%	-24.76%	-10.51%
Max Drawdown (5Y) Largest decline over 5 years	-50.05%	-38.13%	-11.92%
Max Drawdown (10Y) Largest decline over 10 years	-50.29%	-39.16%	-11.13%
Current Drawdown Current decline from peak	0.00%	-0.59%	+0.59%
Average Drawdown Average peak-to-trough decline	-11.66%	-11.14%	-0.52%
Ulcer Index Depth and duration of drawdowns from previous peaks	4.13%	3.51%	+0.62%

Volatility

NESGX vs. WBSIX - Volatility Comparison

Needham Small Cap Growth Fund (NESGX) has a higher volatility of 8.14% compared to William Blair Small Cap Growth Fund (WBSIX) at 5.50%. This indicates that NESGX's price experiences larger fluctuations and is considered to be riskier than WBSIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	NESGX	WBSIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	8.14%	5.50%	+2.64%
Volatility (6M) Calculated over the trailing 6-month period	20.82%	14.42%	+6.40%
Volatility (1Y) Calculated over the trailing 1-year period	30.08%	19.99%	+10.09%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	29.22%	23.85%	+5.37%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	25.80%	23.02%	+2.78%

NESGX vs. WBSIX - Expense Ratio Comparison

NESGX has a 1.85% expense ratio, which is higher than WBSIX's 1.25% expense ratio.

Dividends

NESGX vs. WBSIX - Dividend Comparison

NESGX has not paid dividends to shareholders, while WBSIX's dividend yield for the trailing twelve months is around 6.54%.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
NESGX Needham Small Cap Growth Fund	0.00%	0.00%	0.00%	0.00%	4.16%	25.09%	13.69%	8.43%	22.26%	8.94%	6.67%	2.52%
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 NESGX and WBSIX in my portfolio?

NESGX and WBSIX have a correlation of 0.83, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, NESGX or WBSIX?

NESGX has higher volatility (8.14%) compared to WBSIX (5.50%). In terms of maximum drawdown, NESGX dropped -50.29% vs WBSIX's -62.35%.

Which has better risk-adjusted returns?

NESGX currently has the higher Sharpe Ratio (4.11 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.