BIGIX vs. WBSIX

Last updated Jun 24, 2026

BIGIX (William Blair International Growth Fund Class I) and WBSIX (William Blair Small Cap Growth Fund) are both mutual funds - BIGIX is a Foreign Large Cap Equities fund actively managed by William Blair, while WBSIX is a Small Cap Growth Equities fund managed by William Blair. Over the past 10 years, BIGIX returned 9.53%/yr vs 15.39%/yr for WBSIX. A 0.63 correlation means they provide meaningful diversification when combined. BIGIX charges 0.90%/yr vs 1.25%/yr for WBSIX.

Performance

BIGIX vs. WBSIX - Performance Comparison

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

Returns By Period

The year-to-date returns for both investments are quite close, with BIGIX having a 18.66% return and WBSIX slightly higher at 19.52%. Over the past 10 years, BIGIX has underperformed WBSIX with an annualized return of 9.53%, while WBSIX has yielded a comparatively higher 15.39% annualized return.

BIGIX

• 1D: 0.75%
• 1M: 5.34%
• YTD: 18.66%
• 6M: 18.96%
• 1Y: 28.55%
• 3Y*: 14.86%
• 5Y*: 3.64%
• 10Y*: 9.53%

WBSIX

• 1D: 0.25%
• 1M: 6.39%
• YTD: 19.52%
• 6M: 17.13%
• 1Y: 32.93%
• 3Y*: 21.13%
• 5Y*: 8.19%
• 10Y*: 15.39%

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

BIGIX vs. WBSIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
BIGIX William Blair International Growth Fund Class I	18.66%	18.17%	2.38%	15.43%	-28.46%	8.95%	32.01%	30.66%	-17.71%	29.48%
WBSIX William Blair Small Cap Growth Fund	19.52%	3.03%	32.88%	16.38%	-21.46%	12.64%	38.87%	22.53%	-2.08%	26.81%

Correlation

The correlation between BIGIX and WBSIX is 0.60, which is moderate. They share some common price drivers but move independently often enough to provide real diversification benefit when combined.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.60
Correlation (3Y) Calculated over the trailing 3-year period	0.63
Correlation (5Y) Calculated over the trailing 5-year period	0.67
Correlation (10Y) Calculated over the trailing 10-year period	0.62
Correlation (All Time) Calculated using the full available price history since Dec 27, 1999	0.63

The correlation between BIGIX and WBSIX has been stable across timeframes, ranging from 0.60 to 0.67 - a consistent structural relationship.

Return for Risk

BIGIX vs. WBSIX — Risk / Return Rank

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

BIGIX

BIGIX Risk / Return Rank: 42
BIGIX Sharpe Ratio Rank: 43
BIGIX Sortino Ratio Rank: 39
BIGIX Omega Ratio Rank: 49
BIGIX Calmar Ratio Rank: 38
BIGIX Martin Ratio Rank: 41

WBSIX

WBSIX Risk / Return Rank: 42
WBSIX Sharpe Ratio Rank: 37
WBSIX Sortino Ratio Rank: 37
WBSIX Omega Ratio Rank: 32
WBSIX Calmar Ratio Rank: 54
WBSIX Martin Ratio Rank: 50

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.

BIGIX vs. WBSIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for William Blair International Growth Fund Class I (BIGIX) 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.

Values are calculated on a 1-year rolling basis and updated daily. Risk-adjusted metrics are more stable over longer periods — use the period switch above to explore them.

	BIGIX	WBSIX	Difference
Sharpe ratio: Return per unit of total volatility	1.77	1.66	+0.11
Sortino ratio: Return per unit of downside risk	2.42	2.37	+0.05
Omega ratio: Gain probability vs. loss probability	1.35	1.28	+0.07
Calmar ratio: Return relative to maximum drawdown	2.21	2.69	-0.48
Martin ratio: Return relative to average drawdown	8.23	9.68	-1.45

BIGIX vs. WBSIX - Sharpe Ratio Comparison

The current BIGIX Sharpe Ratio is 1.77, which is comparable to the WBSIX Sharpe Ratio of 1.66. The chart below compares the historical Sharpe Ratios of BIGIX 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.

Drawdowns

BIGIX vs. WBSIX - Drawdown Comparison

The maximum BIGIX drawdown since its inception was -65.22%, roughly equal to the maximum WBSIX drawdown of -62.35%. Use the drawdown chart below to compare losses from any high point for BIGIX and WBSIX.

Drawdown Indicators

	BIGIX	WBSIX	Difference
Max Drawdown Largest peak-to-trough decline	-65.22%	-62.35%	-2.87%
Max Drawdown (1Y) Largest decline over 1 year	-13.21%	-12.75%	-0.46%
Max Drawdown (3Y) Largest decline over 3 years	-17.09%	-24.76%	+7.67%
Max Drawdown (5Y) Largest decline over 5 years	-41.03%	-38.13%	-2.90%
Max Drawdown (10Y) Largest decline over 10 years	-41.03%	-39.16%	-1.87%
Current Drawdown Current decline from peak	0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-17.13%	-11.12%	-6.01%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.53%	3.53%	0.00%

Volatility

BIGIX vs. WBSIX - Volatility Comparison

William Blair International Growth Fund Class I (BIGIX) has a higher volatility of 7.59% compared to William Blair Small Cap Growth Fund (WBSIX) at 6.86%. This indicates that BIGIX'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

	BIGIX	WBSIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	7.59%	6.86%	+0.73%
Volatility (6M) Calculated over the trailing 6-month period	14.54%	15.40%	-0.86%
Volatility (1Y) Calculated over the trailing 1-year period	16.55%	20.77%	-4.22%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	16.98%	23.98%	-7.00%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	17.31%	23.09%	-5.78%

BIGIX vs. WBSIX - Expense Ratio Comparison

BIGIX has a 0.90% expense ratio, which is lower than WBSIX's 1.25% expense ratio.

Dividends

BIGIX vs. WBSIX - Dividend Comparison

BIGIX's dividend yield for the trailing twelve months is around 15.55%, more than WBSIX's 6.26% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
BIGIX William Blair International Growth Fund Class I	15.55%	18.45%	7.49%	3.52%	7.84%	11.41%	1.11%	1.29%	9.05%	1.54%	1.80%	1.18%
WBSIX William Blair Small Cap Growth Fund	6.26%	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 BIGIX and WBSIX in my portfolio?

BIGIX and WBSIX have a correlation of 0.60, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, BIGIX or WBSIX?

BIGIX has higher volatility (7.59%) compared to WBSIX (6.86%). In terms of maximum drawdown, BIGIX dropped -65.22% vs WBSIX's -62.35%.

Which has better risk-adjusted returns?

BIGIX currently has the higher Sharpe Ratio (1.77 vs 1.66), 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.