WBSIX vs. WSMDX

Last updated Jun 3, 2026

WBSIX (William Blair Small Cap Growth Fund) and WSMDX (William Blair Small-Mid Cap Growth Fund) are both mutual funds - WBSIX is a Small Cap Growth Equities fund managed by William Blair, while WSMDX is a Mid Cap Growth Equities fund managed by William Blair. Over the past 10 years, WBSIX returned 14.65%/yr vs 12.41%/yr for WSMDX. Their correlation of 0.94 suggests significant overlap in exposure. WBSIX charges 1.25%/yr vs 1.10%/yr for WSMDX.

Performance

WBSIX vs. WSMDX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in William Blair Small Cap Growth Fund (WBSIX) and William Blair Small-Mid Cap Growth Fund (WSMDX). 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 higher than WSMDX's 11.78% return. Over the past 10 years, WBSIX has outperformed WSMDX with an annualized return of 14.65%, while WSMDX has yielded a comparatively lower 12.41% annualized 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%

WSMDX

• 1D: 0.13%
• 1M: 3.97%
• YTD: 11.78%
• 6M: 11.21%
• 1Y: 25.91%
• 3Y*: 16.52%
• 5Y*: 6.34%
• 10Y*: 12.41%

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

WBSIX vs. WSMDX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
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%
WSMDX William Blair Small-Mid Cap Growth Fund	11.78%	0.63%	27.55%	18.14%	-22.98%	8.28%	32.38%	30.81%	-2.18%	28.85%

Correlation

The correlation between WBSIX and WSMDX 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 (10Y) Calculated over the trailing 10-year period	0.95
Correlation (All Time) Calculated using the full available price history since Dec 31, 2003	0.94

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

Return for Risk

WBSIX vs. WSMDX — 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

WSMDX

WSMDX Risk / Return Rank: 29
WSMDX Sharpe Ratio Rank: 25
WSMDX Sortino Ratio Rank: 25
WSMDX Omega Ratio Rank: 22
WSMDX Calmar Ratio Rank: 36
WSMDX Martin Ratio Rank: 39

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. WSMDX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for William Blair Small Cap Growth Fund (WBSIX) and William Blair Small-Mid Cap Growth Fund (WSMDX). 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	WSMDX	Difference
Sharpe ratio Return per unit of total volatility	1.62	1.46	+0.16
Sortino ratio Return per unit of downside risk	2.34	2.11	+0.23
Omega ratio Gain probability vs. loss probability	1.27	1.25	+0.02
Calmar ratio Return relative to maximum drawdown	2.51	2.30	+0.20
Martin ratio Return relative to average drawdown	9.11	8.53	+0.58
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. WSMDX - Sharpe Ratio Comparison

The current WBSIX Sharpe Ratio is 1.62, which is comparable to the WSMDX Sharpe Ratio of 1.46. The chart below compares the historical Sharpe Ratios of WBSIX and WSMDX, 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	WSMDX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.62	1.46	+0.16
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.33	0.28	+0.06
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.64	0.57	+0.07
Sharpe Ratio (All Time) Calculated using the full available price history	0.54	0.54	0.00

Drawdowns

WBSIX vs. WSMDX - Drawdown Comparison

The maximum WBSIX drawdown since its inception was -62.35%, which is greater than WSMDX's maximum drawdown of -50.33%. Use the drawdown chart below to compare losses from any high point for WBSIX and WSMDX.

Drawdown Indicators

	WBSIX	WSMDX	Difference
Max Drawdown Largest peak-to-trough decline	-62.35%	-50.33%	-12.02%
Max Drawdown (1Y) Largest decline over 1 year	-12.75%	-11.50%	-1.25%
Max Drawdown (3Y) Largest decline over 3 years	-24.76%	-25.63%	+0.87%
Max Drawdown (5Y) Largest decline over 5 years	-38.13%	-36.89%	-1.24%
Max Drawdown (10Y) Largest decline over 10 years	-39.16%	-36.89%	-2.27%
Current Drawdown Current decline from peak	-0.59%	0.00%	-0.59%
Average Drawdown Average peak-to-trough decline	-11.14%	-8.46%	-2.68%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.51%	3.11%	+0.40%

Volatility

WBSIX vs. WSMDX - Volatility Comparison

William Blair Small Cap Growth Fund (WBSIX) and William Blair Small-Mid Cap Growth Fund (WSMDX) have volatilities of 5.50% and 5.45%, 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

	WBSIX	WSMDX	Difference
Volatility (1M) Calculated over the trailing 1-month period	5.50%	5.45%	+0.05%
Volatility (6M) Calculated over the trailing 6-month period	14.42%	14.13%	+0.29%
Volatility (1Y) Calculated over the trailing 1-year period	19.99%	18.27%	+1.72%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	23.85%	23.04%	+0.81%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	23.02%	21.94%	+1.08%

WBSIX vs. WSMDX - Expense Ratio Comparison

WBSIX has a 1.25% expense ratio, which is higher than WSMDX's 1.10% expense ratio.

Dividends

WBSIX vs. WSMDX - Dividend Comparison

WBSIX's dividend yield for the trailing twelve months is around 6.54%, more than WSMDX's 2.51% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
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%
WSMDX William Blair Small-Mid Cap Growth Fund	2.51%	2.81%	24.90%	7.89%	3.34%	9.30%	1.66%	7.13%	8.88%	5.33%	2.64%	5.31%

Frequently Asked Questions

Can I hold both WBSIX and WSMDX in my portfolio?

With a correlation of 0.93, WBSIX and WSMDX 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 WSMDX?

WBSIX has higher volatility (5.50%) compared to WSMDX (5.45%). In terms of maximum drawdown, WBSIX dropped -62.35% vs WSMDX's -50.33%.

Which has better risk-adjusted returns?

WBSIX currently has the higher Sharpe Ratio (1.62 vs 1.46), 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.