WBIIX vs. WISIX

Last updated Jun 4, 2026

WBIIX (William Blair Institutional International Growth Fund) and WISIX (William Blair International Small Cap Growth Fund) are both mutual funds - WBIIX is a Foreign Large Cap Equities fund managed by William Blair, while WISIX is a Foreign Small & Mid Cap Equities fund managed by William Blair. Over the past 10 years, WBIIX returned 8.70%/yr vs 6.04%/yr for WISIX. Their correlation of 0.92 suggests significant overlap in exposure. WBIIX charges 0.98%/yr vs 1.23%/yr for WISIX.

Performance

WBIIX vs. WISIX - Performance Comparison

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

Returns By Period

In the year-to-date period, WBIIX achieves a 15.67% return, which is significantly higher than WISIX's 12.59% return. Over the past 10 years, WBIIX has outperformed WISIX with an annualized return of 8.70%, while WISIX has yielded a comparatively lower 6.04% annualized return.

WBIIX

• 1D: 0.67%
• 1M: 6.41%
• YTD: 15.67%
• 6M: 18.01%
• 1Y: 24.35%
• 3Y*: 13.58%
• 5Y*: 3.37%
• 10Y*: 8.70%

WISIX

• 1D: -0.31%
• 1M: 1.67%
• YTD: 12.59%
• 6M: 15.43%
• 1Y: 13.37%
• 3Y*: 10.92%
• 5Y*: 0.64%
• 10Y*: 6.04%

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

WBIIX vs. WISIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
WBIIX William Blair Institutional International Growth Fund	15.67%	18.16%	2.40%	15.23%	-28.39%	9.30%	32.69%	30.75%	-17.49%	29.51%
WISIX William Blair International Small Cap Growth Fund	12.59%	15.31%	0.80%	14.72%	-34.99%	11.01%	29.09%	34.22%	-24.27%	32.71%

Correlation

The correlation between WBIIX and WISIX is 0.84, 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	0.84
Correlation (3Y) Calculated over the trailing 3-year period	0.88
Correlation (5Y) Calculated over the trailing 5-year period	0.91
Correlation (10Y) Calculated over the trailing 10-year period	0.91
Correlation (All Time) Calculated using the full available price history since Nov 3, 2005	0.92

The correlation between WBIIX and WISIX has been stable across timeframes, ranging from 0.84 to 0.92 - a consistent structural relationship.

Return for Risk

WBIIX vs. WISIX — Risk / Return Rank

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

WBIIX

WBIIX Risk / Return Rank: 30
WBIIX Sharpe Ratio Rank: 31
WBIIX Sortino Ratio Rank: 29
WBIIX Omega Ratio Rank: 35
WBIIX Calmar Ratio Rank: 25
WBIIX Martin Ratio Rank: 29

WISIX

WISIX Risk / Return Rank: 12
WISIX Sharpe Ratio Rank: 12
WISIX Sortino Ratio Rank: 12
WISIX Omega Ratio Rank: 13
WISIX Calmar Ratio Rank: 14
WISIX Martin Ratio Rank: 12

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.

WBIIX vs. WISIX - Risk-Adjusted Trends Comparison

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

	WBIIX	WISIX	Difference
Sharpe ratio: Return per unit of total volatility	1.61	0.93	+0.68
Sortino ratio: Return per unit of downside risk	2.25	1.37	+0.87
Omega ratio: Gain probability vs. loss probability	1.31	1.18	+0.13
Calmar ratio: Return relative to maximum drawdown	1.83	1.26	+0.57
Martin ratio: Return relative to average drawdown	6.89	3.49	+3.40
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

WBIIX vs. WISIX - Sharpe Ratio Comparison

The current WBIIX Sharpe Ratio is 1.61, which is higher than the WISIX Sharpe Ratio of 0.93. The chart below compares the historical Sharpe Ratios of WBIIX and WISIX, 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

	WBIIX	WISIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.61	0.93	+0.68
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.20	0.04	+0.17
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.51	0.35	+0.16
Sharpe Ratio (All Time) Calculated using the full available price history	0.44	0.35	+0.09

Drawdowns

WBIIX vs. WISIX - Drawdown Comparison

The maximum WBIIX drawdown since its inception was -65.13%, roughly equal to the maximum WISIX drawdown of -64.84%. Use the drawdown chart below to compare losses from any high point for WBIIX and WISIX.

Drawdown Indicators

	WBIIX	WISIX	Difference
Max Drawdown Largest peak-to-trough decline	-65.13%	-64.84%	-0.29%
Max Drawdown (1Y) Largest decline over 1 year	-13.17%	-10.09%	-3.08%
Max Drawdown (3Y) Largest decline over 3 years	-17.06%	-17.90%	+0.84%
Max Drawdown (5Y) Largest decline over 5 years	-40.91%	-47.76%	+6.85%
Max Drawdown (10Y) Largest decline over 10 years	-40.91%	-47.76%	+6.85%
Current Drawdown Current decline from peak	0.00%	-9.75%	+9.75%
Average Drawdown Average peak-to-trough decline	-14.80%	-16.57%	+1.77%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.48%	3.62%	-0.14%

Volatility

WBIIX vs. WISIX - Volatility Comparison

William Blair Institutional International Growth Fund (WBIIX) has a higher volatility of 5.43% compared to William Blair International Small Cap Growth Fund (WISIX) at 4.53%. This indicates that WBIIX's price experiences larger fluctuations and is considered to be riskier than WISIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	WBIIX	WISIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	5.43%	4.53%	+0.90%
Volatility (6M) Calculated over the trailing 6-month period	12.70%	11.48%	+1.22%
Volatility (1Y) Calculated over the trailing 1-year period	14.98%	13.72%	+1.26%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	16.66%	17.29%	-0.63%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	17.17%	17.36%	-0.19%

WBIIX vs. WISIX - Expense Ratio Comparison

WBIIX has a 0.98% expense ratio, which is lower than WISIX's 1.23% expense ratio.

Dividends

WBIIX vs. WISIX - Dividend Comparison

WBIIX's dividend yield for the trailing twelve months is around 10.83%, more than WISIX's 0.54% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
WBIIX William Blair Institutional International Growth Fund	10.83%	12.53%	7.49%	2.51%	6.57%	16.58%	12.61%	0.95%	11.74%	4.16%	1.15%	1.28%
WISIX William Blair International Small Cap Growth Fund	0.54%	0.61%	1.78%	0.88%	0.21%	16.20%	2.09%	0.31%	13.84%	9.94%	0.36%	2.31%

Frequently Asked Questions

Can I hold both WBIIX and WISIX in my portfolio?

WBIIX and WISIX have a correlation of 0.84, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, WBIIX or WISIX?

WBIIX has higher volatility (5.43%) compared to WISIX (4.53%). In terms of maximum drawdown, WBIIX dropped -65.13% vs WISIX's -64.84%.

Which has better risk-adjusted returns?

WBIIX currently has the higher Sharpe Ratio (1.61 vs 0.93), 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.