WBGSX vs. VFIAX

Last updated Jun 23, 2026

WBGSX (William Blair Growth Fund) and VFIAX (Vanguard 500 Index Fund Admiral Shares) are both mutual funds - WBGSX is a Large Cap Growth Equities fund managed by William Blair, while VFIAX is a S&P 500 fund tracking the S&P 500 Index. Over the past 10 years, WBGSX returned 14.98%/yr vs 15.76%/yr for VFIAX. Their correlation of 0.93 suggests significant overlap in exposure. WBGSX charges 1.20%/yr vs 0.04%/yr for VFIAX.

Performance

WBGSX vs. VFIAX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in William Blair Growth Fund (WBGSX) and Vanguard 500 Index Fund Admiral Shares (VFIAX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, WBGSX achieves a 7.01% return, which is significantly lower than VFIAX's 9.77% return. Over the past 10 years, WBGSX has underperformed VFIAX with an annualized return of 14.98%, while VFIAX has yielded a comparatively higher 15.76% annualized return.

WBGSX

• 1D: 1.70%
• 1M: 1.41%
• YTD: 7.01%
• 6M: 6.22%
• 1Y: 20.65%
• 3Y*: 16.65%
• 5Y*: 8.95%
• 10Y*: 14.98%

VFIAX

• 1D: -0.36%
• 1M: 0.10%
• YTD: 9.77%
• 6M: 8.77%
• 1Y: 25.48%
• 3Y*: 21.36%
• 5Y*: 13.57%
• 10Y*: 15.76%

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

WBGSX vs. VFIAX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
WBGSX William Blair Growth Fund	7.01%	10.69%	21.86%	37.75%	-29.75%	21.71%	36.12%	32.11%	4.88%	24.19%
VFIAX Vanguard 500 Index Fund Admiral Shares	9.77%	17.83%	24.97%	26.24%	-18.16%	28.65%	18.32%	31.46%	-4.45%	21.78%

Correlation

The correlation between WBGSX and VFIAX is 0.92, 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	0.92
Correlation (3Y) Calculated over the trailing 3-year period	0.91
Correlation (5Y) Calculated over the trailing 5-year period	0.93
Correlation (10Y) Calculated over the trailing 10-year period	0.92
Correlation (All Time) Calculated using the full available price history since Nov 13, 2000	0.93

The correlation between WBGSX and VFIAX has been stable across timeframes, ranging from 0.91 to 0.93 - a consistent structural relationship.

Return for Risk

WBGSX vs. VFIAX — Risk / Return Rank

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

WBGSX

WBGSX Risk / Return Rank: 15
WBGSX Sharpe Ratio Rank: 18
WBGSX Sortino Ratio Rank: 17
WBGSX Omega Ratio Rank: 18
WBGSX Calmar Ratio Rank: 11
WBGSX Martin Ratio Rank: 11

VFIAX

VFIAX Risk / Return Rank: 65
VFIAX Sharpe Ratio Rank: 63
VFIAX Sortino Ratio Rank: 57
VFIAX Omega Ratio Rank: 59
VFIAX Calmar Ratio Rank: 68
VFIAX Martin Ratio Rank: 78

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.

WBGSX vs. VFIAX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for William Blair Growth Fund (WBGSX) and Vanguard 500 Index Fund Admiral Shares (VFIAX). 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	VFIAX	Difference
Sharpe ratio: Return per unit of total volatility	1.13	2.15	-1.02
Sortino ratio: Return per unit of downside risk	1.60	2.91	-1.31
Omega ratio: Gain probability vs. loss probability	1.21	1.39	-0.18
Calmar ratio: Return relative to maximum drawdown	1.01	3.01	-2.00
Martin ratio: Return relative to average drawdown	2.87	13.60	-10.73

WBGSX vs. VFIAX - Sharpe Ratio Comparison

The current WBGSX Sharpe Ratio is 1.13, which is lower than the VFIAX Sharpe Ratio of 2.15. The chart below compares the historical Sharpe Ratios of WBGSX and VFIAX, 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. VFIAX - Drawdown Comparison

The maximum WBGSX drawdown since its inception was -53.05%, roughly equal to the maximum VFIAX drawdown of -55.20%. Use the drawdown chart below to compare losses from any high point for WBGSX and VFIAX.

Drawdown Indicators

	WBGSX	VFIAX	Difference
Max Drawdown Largest peak-to-trough decline	-53.05%	-55.20%	+2.15%
Max Drawdown (1Y) Largest decline over 1 year	-19.70%	-8.90%	-10.80%
Max Drawdown (3Y) Largest decline over 3 years	-25.45%	-18.75%	-6.70%
Max Drawdown (5Y) Largest decline over 5 years	-36.90%	-24.53%	-12.37%
Max Drawdown (10Y) Largest decline over 10 years	-36.90%	-33.83%	-3.07%
Current Drawdown Current decline from peak	-3.37%	-1.72%	-1.65%
Average Drawdown Average peak-to-trough decline	-11.51%	-9.38%	-2.13%
Ulcer Index Depth and duration of drawdowns from previous peaks	6.94%	1.97%	+4.97%

Volatility

WBGSX vs. VFIAX - Volatility Comparison

William Blair Growth Fund (WBGSX) has a higher volatility of 7.17% compared to Vanguard 500 Index Fund Admiral Shares (VFIAX) at 4.67%. This indicates that WBGSX's price experiences larger fluctuations and is considered to be riskier than VFIAX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	WBGSX	VFIAX	Difference
Volatility (1M) Calculated over the trailing 1-month period	7.17%	4.67%	+2.50%
Volatility (6M) Calculated over the trailing 6-month period	13.87%	9.84%	+4.03%
Volatility (1Y) Calculated over the trailing 1-year period	17.66%	12.50%	+5.16%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	21.66%	16.99%	+4.67%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	20.62%	18.11%	+2.51%

WBGSX vs. VFIAX - Expense Ratio Comparison

WBGSX has a 1.20% expense ratio, which is higher than VFIAX's 0.04% expense ratio.

Dividends

WBGSX vs. VFIAX - Dividend Comparison

WBGSX's dividend yield for the trailing twelve months is around 41.08%, more than VFIAX's 1.03% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
VFIAX Vanguard 500 Index Fund Admiral Shares	1.03%	1.12%	1.24%	1.45%	1.68%	1.24%	1.53%	1.87%	2.05%	1.78%	2.02%	2.10%
WBGSX William Blair Growth Fund	41.08%	43.96%	34.53%	12.73%	4.59%	14.82%	15.07%	10.27%	38.86%	38.00%	8.81%	13.92%

Frequently Asked Questions

Can I hold both WBGSX and VFIAX in my portfolio?

With a correlation of 0.92, WBGSX and VFIAX 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, WBGSX or VFIAX?

WBGSX has higher volatility (7.17%) compared to VFIAX (4.67%). In terms of maximum drawdown, WBGSX dropped -53.05% vs VFIAX's -55.20%.

Which has better risk-adjusted returns?

VFIAX currently has the higher Sharpe Ratio (2.15 vs 1.13), 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.