WBSIX vs. FECGX

Last updated Jun 3, 2026

WBSIX (William Blair Small Cap Growth Fund) and FECGX (Fidelity Small Cap Growth Index Fund) are both Small Cap Growth Equities funds. Over the past 5 years, WBSIX returned 7.93%/yr vs 6.22%/yr for FECGX. With a 0.96 correlation, they move nearly in lockstep. WBSIX charges 1.25%/yr vs 0.05%/yr for FECGX.

Performance

WBSIX vs. FECGX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in William Blair Small Cap Growth Fund (WBSIX) and Fidelity Small Cap Growth Index Fund (FECGX). 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 FECGX's 18.46% 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%

FECGX

• 1D: 0.87%
• 1M: 5.85%
• YTD: 18.46%
• 6M: 16.79%
• 1Y: 39.39%
• 3Y*: 18.78%
• 5Y*: 6.22%
• 10Y*: —

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

WBSIX vs. FECGX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019
WBSIX William Blair Small Cap Growth Fund	14.56%	3.03%	32.88%	16.38%	-21.46%	12.64%	38.87%	1.68%
FECGX Fidelity Small Cap Growth Index Fund	18.46%	13.04%	15.26%	18.90%	-26.17%	2.83%	34.41%	7.11%

Correlation

The correlation between WBSIX and FECGX is 0.93, 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	0.93
Correlation (3Y) Calculated over the trailing 3-year period	0.95
Correlation (5Y) Calculated over the trailing 5-year period	0.96
Correlation (All Time) Calculated using the full available price history since Jul 18, 2019	0.96

The correlation between WBSIX and FECGX has been stable across timeframes, ranging from 0.93 to 0.96 - a consistent structural relationship.

Return for Risk

WBSIX vs. FECGX — 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

FECGX

FECGX Risk / Return Rank: 45
FECGX Sharpe Ratio Rank: 45
FECGX Sortino Ratio Rank: 41
FECGX Omega Ratio Rank: 37
FECGX Calmar Ratio Rank: 55
FECGX Martin Ratio Rank: 49

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. FECGX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for William Blair Small Cap Growth Fund (WBSIX) and Fidelity Small Cap Growth Index Fund (FECGX). 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	FECGX	Difference
Sharpe ratio Return per unit of total volatility	1.62	1.96	-0.35
Sortino ratio Return per unit of downside risk	2.34	2.68	-0.34
Omega ratio Gain probability vs. loss probability	1.27	1.32	-0.05
Calmar ratio Return relative to maximum drawdown	2.51	2.83	-0.32
Martin ratio Return relative to average drawdown	9.11	10.20	-1.09
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. FECGX - Sharpe Ratio Comparison

The current WBSIX Sharpe Ratio is 1.62, which is comparable to the FECGX Sharpe Ratio of 1.96. The chart below compares the historical Sharpe Ratios of WBSIX and FECGX, 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	FECGX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.62	1.96	-0.35
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.33	0.25	+0.08
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.64	—	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.54	0.39	+0.15

Drawdowns

WBSIX vs. FECGX - Drawdown Comparison

The maximum WBSIX drawdown since its inception was -62.35%, which is greater than FECGX's maximum drawdown of -41.85%. Use the drawdown chart below to compare losses from any high point for WBSIX and FECGX.

Drawdown Indicators

	WBSIX	FECGX	Difference
Max Drawdown Largest peak-to-trough decline	-62.35%	-41.85%	-20.50%
Max Drawdown (1Y) Largest decline over 1 year	-12.75%	-14.81%	+2.06%
Max Drawdown (3Y) Largest decline over 3 years	-24.76%	-28.45%	+3.69%
Max Drawdown (5Y) Largest decline over 5 years	-38.13%	-40.34%	+2.21%
Max Drawdown (10Y) Largest decline over 10 years	-39.16%	—	—
Current Drawdown Current decline from peak	-0.59%	0.00%	-0.59%
Average Drawdown Average peak-to-trough decline	-11.14%	-15.76%	+4.62%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.51%	4.10%	-0.59%

Volatility

WBSIX vs. FECGX - Volatility Comparison

The current volatility for William Blair Small Cap Growth Fund (WBSIX) is 5.50%, while Fidelity Small Cap Growth Index Fund (FECGX) has a volatility of 6.44%. This indicates that WBSIX experiences smaller price fluctuations and is considered to be less risky than FECGX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	WBSIX	FECGX	Difference
Volatility (1M) Calculated over the trailing 1-month period	5.50%	6.44%	-0.94%
Volatility (6M) Calculated over the trailing 6-month period	14.42%	15.86%	-1.44%
Volatility (1Y) Calculated over the trailing 1-year period	19.99%	21.35%	-1.36%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	23.85%	24.54%	-0.69%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	23.02%	27.19%	-4.17%

WBSIX vs. FECGX - Expense Ratio Comparison

WBSIX has a 1.25% expense ratio, which is higher than FECGX's 0.05% expense ratio.

Dividends

WBSIX vs. FECGX - Dividend Comparison

WBSIX's dividend yield for the trailing twelve months is around 6.54%, more than FECGX's 0.46% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FECGX Fidelity Small Cap Growth Index Fund	0.46%	0.54%	1.25%	0.81%	0.80%	3.43%	1.00%	0.29%	0.00%	0.00%	0.00%	0.00%
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 FECGX in my portfolio?

With a correlation of 0.93, WBSIX and FECGX move almost identically. Holding both adds very little diversification - you're essentially doubling your position in the same market segment. Choosing one is usually more capital-efficient.

Which is riskier, WBSIX or FECGX?

FECGX has higher volatility (6.44%) compared to WBSIX (5.50%). In terms of maximum drawdown, WBSIX dropped -62.35% vs FECGX's -41.85%.

Which has better risk-adjusted returns?

FECGX currently has the higher Sharpe Ratio (1.96 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.