WBGSX vs. WBIIX

Last updated Aug 1, 2026

WBGSX (William Blair Growth Fund) and WBIIX (William Blair Institutional International Growth Fund) are both mutual funds - WBGSX is a Large Cap Growth Equities fund managed by William Blair, while WBIIX is a Foreign Large Cap Equities fund managed by William Blair. Over the past 10 years, WBGSX returned 14.02%/yr vs 8.14%/yr for WBIIX. Their 0.68 correlation means they have sometimes moved together and sometimes differently. WBGSX charges 1.20%/yr vs 0.98%/yr for WBIIX.

Performance

WBGSX vs. WBIIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in William Blair Growth Fund (WBGSX) and William Blair Institutional International Growth Fund (WBIIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, WBGSX achieves a 3.28% return, which is significantly lower than WBIIX's 10.79% return. Over the past 10 years, WBGSX has outperformed WBIIX with an annualized return of 14.02%, while WBIIX has yielded a comparatively lower 8.14% annualized return.

WBGSX

• 1D: 2.82%
• 1M: -1.84%
• 6M: 4.85%
• YTD: 3.28%
• 1Y: 10.19%
• 3Y*: 13.88%
• 5Y*: 7.13%
• 10Y*: 14.02%
• ALL TIME*: 9.56%

WBIIX

• 1D: 3.11%
• 1M: -4.04%
• 6M: 4.81%
• YTD: 10.79%
• 1Y: 19.03%
• 3Y*: 11.18%
• 5Y*: 1.85%
• 10Y*: 8.14%
• ALL TIME*: 7.96%

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

Liquidity Comparison

Position	Avg. Volume Value (2W)	Avg. Volume Value (1M)	Avg. Volume Value (3M)
WBGSX William Blair Growth Fund	$0.00	$0.00	$0.00
WBIIX William Blair Institutional International Growth Fund	$0.00	$0.00	$0.00

WBGSX vs. WBIIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
WBGSX William Blair Growth Fund	3.28%	10.69%	21.86%	37.75%	-29.75%	21.71%	36.12%	32.11%	4.88%	24.19%
WBIIX William Blair Institutional International Growth Fund	10.79%	18.16%	2.40%	15.23%	-28.39%	9.30%	32.69%	30.75%	-17.49%	29.51%

Correlation

The correlation between WBGSX and WBIIX is 0.66, which is moderate. They have sometimes moved together and sometimes differently, sharing some price drivers without tracking each other closely.

	Correlation
Correlation (1Y) Focuses on recent behavior, but can change the most.	0.66
Correlation (3Y) Balances recent behavior with more history.	0.64
Correlation (5Y) Shows whether the relationship held over a longer period.	0.70
Correlation (10Y) Provides a long-term view across more market conditions.	0.67
Correlation (All Time) Calculated using the full available price history since Jul 29, 2002	0.68

The correlation between WBGSX and WBIIX has been stable across timeframes, ranging from 0.64 to 0.70 - a consistent structural relationship.

Return for Risk

WBGSX vs. WBIIX — Risk / Return Rank

Compare historical risk-adjusted metric ranks over the past 12 months.

WBGSX

WBGSX Risk / Return Rank: 9
WBGSX Sharpe Ratio Rank: 10
WBGSX Sortino Ratio Rank: 10
WBGSX Omega Ratio Rank: 10
WBGSX Calmar Ratio Rank: 8
WBGSX Martin Ratio Rank: 8

WBIIX

WBIIX Risk / Return Rank: 29
WBIIX Sharpe Ratio Rank: 28
WBIIX Sortino Ratio Rank: 27
WBIIX Omega Ratio Rank: 31
WBIIX Calmar Ratio Rank: 28
WBIIX Martin Ratio Rank: 29

The rank (0–100) uses a weighted average of the Sharpe, Sortino, Omega, Calmar, and Martin percentile ranks for the trailing 12 months. Higher means stronger historical risk-adjusted performance within the peer group.

WBGSX vs. WBIIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for William Blair Growth Fund (WBGSX) and William Blair Institutional International Growth Fund (WBIIX). 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.

	WBGSX	WBIIX	Difference
Sharpe ratio: Return per unit of total volatility	0.37	0.99	-0.62
Sortino ratio: Return per unit of downside risk	0.63	1.44	-0.81
Omega ratio: Gain probability vs. loss probability	1.08	1.20	-0.12
Calmar ratio: Return relative to maximum drawdown	0.35	1.33	-0.99
Martin ratio: Return relative to average drawdown	0.95	4.51	-3.56

WBGSX vs. WBIIX - Sharpe Ratio Comparison

The current WBGSX Sharpe Ratio is 0.37, which is lower than the WBIIX Sharpe Ratio of 0.99. The chart below compares the historical Sharpe Ratios of WBGSX and WBIIX, 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

WBGSX vs. WBIIX - Drawdown Comparison

The maximum WBGSX drawdown since its inception was -53.05%, smaller than the maximum WBIIX drawdown of -65.13%. Use the drawdown chart below to compare losses from any high point for WBGSX and WBIIX.

Drawdown Indicators

	WBGSX	WBIIX	Difference
Max Drawdown Largest peak-to-trough decline	-53.05%	-65.13%	+12.08%
Max Drawdown (1Y) Largest decline over 1 year	-19.70%	-13.17%	-6.53%
Max Drawdown (3Y) Largest decline over 3 years	-25.45%	-17.06%	-8.39%
Max Drawdown (5Y) Largest decline over 5 years	-36.90%	-40.91%	+4.01%
Max Drawdown (10Y) Largest decline over 10 years	-36.90%	-40.91%	+4.01%
Current Drawdown Current decline from peak	-6.74%	-6.58%	-0.16%
Average Drawdown Average peak-to-trough decline	-11.50%	-14.73%	+3.23%
Ulcer Index Depth and duration of drawdowns from previous peaks	7.17%	3.89%	+3.28%

Volatility

WBGSX vs. WBIIX - Volatility Comparison

William Blair Growth Fund (WBGSX) and William Blair Institutional International Growth Fund (WBIIX) have volatilities of 5.92% and 5.88%, respectively, indicating that both stocks experience similar levels of price fluctuations. This suggests that the risk associated with both stocks, as measured by volatility, is nearly the same. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	WBGSX	WBIIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	5.92%	5.88%	+0.04%
Volatility (6M) Calculated over the trailing 6-month period	14.68%	15.72%	-1.04%
Volatility (1Y) Calculated over the trailing 1-year period	18.53%	17.73%	+0.80%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	21.80%	17.15%	+4.65%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	20.65%	17.18%	+3.47%

WBGSX vs. WBIIX - Expense Ratio Comparison

WBGSX has a 1.20% expense ratio, which is higher than WBIIX's 0.98% expense ratio.

Dividends

WBGSX vs. WBIIX - Dividend Comparison

WBGSX's dividend yield for the trailing twelve months is around 42.57%, more than WBIIX's 11.31% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
WBGSX William Blair Growth Fund	42.57%	43.96%	34.53%	12.73%	4.59%	14.82%	15.07%	10.27%	38.86%	38.00%	8.81%	13.92%
WBIIX William Blair Institutional International Growth Fund	11.31%	12.53%	7.49%	2.51%	6.57%	16.58%	12.61%	0.95%	11.74%	4.16%	1.15%	1.28%

Frequently Asked Questions

Can I hold both WBGSX and WBIIX in my portfolio?

WBGSX and WBIIX have a correlation of 0.66, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, WBGSX or WBIIX?

WBGSX has higher volatility (5.92%) compared to WBIIX (5.88%). In terms of maximum drawdown, WBGSX dropped -53.05% vs WBIIX's -65.13%.

Which has better risk-adjusted returns?

WBIIX currently has the higher Sharpe Ratio (0.99 vs 0.37), 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.