WBGSX vs. ACIHX

Last updated Jun 3, 2026

WBGSX (William Blair Growth Fund) and ACIHX (American Century Growth Fund G Class) are both Large Cap Growth Equities funds. Over the past 3 years, WBGSX returned 18.99%/yr vs 23.27%/yr for ACIHX. Their correlation of 0.95 suggests significant overlap in exposure. WBGSX charges 1.20%/yr vs 0.01%/yr for ACIHX.

Performance

WBGSX vs. ACIHX - Performance Comparison

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

Returns By Period

In the year-to-date period, WBGSX achieves a 10.75% return, which is significantly higher than ACIHX's 9.51% return.

WBGSX

• 1D: 1.37%
• 1M: 9.28%
• YTD: 10.75%
• 6M: 9.39%
• 1Y: 27.06%
• 3Y*: 18.99%
• 5Y*: 10.20%
• 10Y*: 15.17%

ACIHX

• 1D: 1.13%
• 1M: 8.30%
• YTD: 9.51%
• 6M: 8.44%
• 1Y: 29.23%
• 3Y*: 23.27%
• 5Y*: —
• 10Y*: —

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

WBGSX vs. ACIHX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022
WBGSX William Blair Growth Fund	10.75%	10.69%	21.86%	37.75%	-6.56%
ACIHX American Century Growth Fund G Class	9.51%	16.26%	27.35%	44.64%	-6.24%

Correlation

The correlation between WBGSX and ACIHX 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	0.92
Correlation (All Time) Calculated using the full available price history since May 17, 2022	0.95

The correlation between WBGSX and ACIHX has been stable across timeframes, ranging from 0.92 to 0.95 - a consistent structural relationship.

Return for Risk

WBGSX vs. ACIHX — Risk / Return Rank

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

WBGSX

WBGSX Risk / Return Rank: 24
WBGSX Sharpe Ratio Rank: 33
WBGSX Sortino Ratio Rank: 29
WBGSX Omega Ratio Rank: 31
WBGSX Calmar Ratio Rank: 15
WBGSX Martin Ratio Rank: 14

ACIHX

ACIHX Risk / Return Rank: 33
ACIHX Sharpe Ratio Rank: 43
ACIHX Sortino Ratio Rank: 38
ACIHX Omega Ratio Rank: 39
ACIHX Calmar Ratio Rank: 23
ACIHX Martin Ratio Rank: 23

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. ACIHX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for William Blair Growth Fund (WBGSX) and American Century Growth Fund G Class (ACIHX). 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.

	WBGSX	ACIHX	Difference
Sharpe ratio Return per unit of total volatility	1.67	1.92	-0.25
Sortino ratio Return per unit of downside risk	2.27	2.59	-0.32
Omega ratio Gain probability vs. loss probability	1.29	1.33	-0.04
Calmar ratio Return relative to maximum drawdown	1.44	1.83	-0.39
Martin ratio Return relative to average drawdown	4.11	6.15	-2.03
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

WBGSX vs. ACIHX - Sharpe Ratio Comparison

The current WBGSX Sharpe Ratio is 1.67, which is comparable to the ACIHX Sharpe Ratio of 1.92. The chart below compares the historical Sharpe Ratios of WBGSX and ACIHX, 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

	WBGSX	ACIHX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.67	1.92	-0.25
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.48	—	—
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.74	—	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.51	1.03	-0.52

Drawdowns

WBGSX vs. ACIHX - Drawdown Comparison

The maximum WBGSX drawdown since its inception was -53.05%, which is greater than ACIHX's maximum drawdown of -24.00%. Use the drawdown chart below to compare losses from any high point for WBGSX and ACIHX.

Drawdown Indicators

	WBGSX	ACIHX	Difference
Max Drawdown Largest peak-to-trough decline	-53.05%	-24.00%	-29.05%
Max Drawdown (1Y) Largest decline over 1 year	-19.70%	-16.40%	-3.30%
Max Drawdown (3Y) Largest decline over 3 years	-25.45%	-24.00%	-1.45%
Max Drawdown (5Y) Largest decline over 5 years	-36.90%	—	—
Max Drawdown (10Y) Largest decline over 10 years	-36.90%	—	—
Current Drawdown Current decline from peak	0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-11.52%	-4.89%	-6.63%
Ulcer Index Depth and duration of drawdowns from previous peaks	6.87%	4.87%	+2.00%

Volatility

WBGSX vs. ACIHX - Volatility Comparison

William Blair Growth Fund (WBGSX) has a higher volatility of 4.48% compared to American Century Growth Fund G Class (ACIHX) at 3.32%. This indicates that WBGSX's price experiences larger fluctuations and is considered to be riskier than ACIHX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	WBGSX	ACIHX	Difference
Volatility (1M) Calculated over the trailing 1-month period	4.48%	3.32%	+1.16%
Volatility (6M) Calculated over the trailing 6-month period	12.65%	11.91%	+0.74%
Volatility (1Y) Calculated over the trailing 1-year period	16.78%	15.73%	+1.05%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	21.50%	21.06%	+0.44%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	20.54%	21.06%	-0.52%

WBGSX vs. ACIHX - Expense Ratio Comparison

WBGSX has a 1.20% expense ratio, which is higher than ACIHX's 0.01% expense ratio.

Dividends

WBGSX vs. ACIHX - Dividend Comparison

WBGSX's dividend yield for the trailing twelve months is around 39.70%, more than ACIHX's 14.56% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
ACIHX American Century Growth Fund G Class	14.56%	15.95%	5.65%	4.61%	2.86%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%
WBGSX William Blair Growth Fund	39.70%	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 ACIHX in my portfolio?

With a correlation of 0.92, WBGSX and ACIHX 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 ACIHX?

WBGSX has higher volatility (4.48%) compared to ACIHX (3.32%). In terms of maximum drawdown, WBGSX dropped -53.05% vs ACIHX's -24.00%.

Which has better risk-adjusted returns?

ACIHX currently has the higher Sharpe Ratio (1.92 vs 1.67), 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.