VMGAX vs. ACIHX

Last updated Jun 4, 2026

VMGAX (Vanguard Mega Cap Growth Index Fund Institutional Shares) and ACIHX (American Century Growth Fund G Class) are both Large Cap Growth Equities funds. Over the past 3 years, VMGAX returned 27.29%/yr vs 23.07%/yr for ACIHX. With a 0.99 correlation, they move nearly in lockstep. VMGAX charges 0.06%/yr vs 0.01%/yr for ACIHX.

Performance

VMGAX vs. ACIHX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Vanguard Mega Cap Growth Index Fund Institutional Shares (VMGAX) 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, VMGAX achieves a 11.29% return, which is significantly higher than ACIHX's 8.95% return.

VMGAX

• 1D: -0.29%
• 1M: 8.54%
• YTD: 11.29%
• 6M: 10.76%
• 1Y: 31.60%
• 3Y*: 27.29%
• 5Y*: 16.86%
• 10Y*: 19.39%

ACIHX

• 1D: -0.51%
• 1M: 7.84%
• YTD: 8.95%
• 6M: 8.02%
• 1Y: 27.75%
• 3Y*: 23.07%
• 5Y*: —
• 10Y*: —

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

VMGAX vs. ACIHX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022
VMGAX Vanguard Mega Cap Growth Index Fund Institutional Shares	11.29%	20.73%	32.98%	51.57%	-9.79%
ACIHX American Century Growth Fund G Class	8.95%	16.26%	27.35%	44.64%	-6.24%

Correlation

The correlation between VMGAX and ACIHX is 0.98 - these two move nearly in lockstep. At this level, holding both provides almost no diversification benefit. If you already own one, adding the other does little to reduce portfolio risk.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.98
Correlation (3Y) Calculated over the trailing 3-year period	0.99
Correlation (All Time) Calculated using the full available price history since May 17, 2022	0.99

The correlation between VMGAX and ACIHX has been stable across timeframes, ranging from 0.98 to 0.99 - a consistent structural relationship.

Return for Risk

VMGAX vs. ACIHX — Risk / Return Rank

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

VMGAX

VMGAX Risk / Return Rank: 37
VMGAX Sharpe Ratio Rank: 47
VMGAX Sortino Ratio Rank: 42
VMGAX Omega Ratio Rank: 42
VMGAX Calmar Ratio Rank: 27
VMGAX Martin Ratio Rank: 28

ACIHX

ACIHX Risk / Return Rank: 31
ACIHX Sharpe Ratio Rank: 40
ACIHX Sortino Ratio Rank: 36
ACIHX Omega Ratio Rank: 36
ACIHX Calmar Ratio Rank: 22
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.

VMGAX vs. ACIHX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Vanguard Mega Cap Growth Index Fund Institutional Shares (VMGAX) 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.

	VMGAX	ACIHX	Difference
Sharpe ratio Return per unit of total volatility	2.01	1.83	+0.19
Sortino ratio Return per unit of downside risk	2.71	2.48	+0.23
Omega ratio Gain probability vs. loss probability	1.35	1.32	+0.03
Calmar ratio Return relative to maximum drawdown	1.95	1.75	+0.20
Martin ratio Return relative to average drawdown	6.74	5.88	+0.86
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

VMGAX vs. ACIHX - Sharpe Ratio Comparison

The current VMGAX Sharpe Ratio is 2.01, which is comparable to the ACIHX Sharpe Ratio of 1.83. The chart below compares the historical Sharpe Ratios of VMGAX 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

	VMGAX	ACIHX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.01	1.83	+0.19
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.75	—	—
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.89	—	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.65	1.02	-0.37

Drawdowns

VMGAX vs. ACIHX - Drawdown Comparison

The maximum VMGAX drawdown since its inception was -47.97%, which is greater than ACIHX's maximum drawdown of -24.00%. Use the drawdown chart below to compare losses from any high point for VMGAX and ACIHX.

Drawdown Indicators

	VMGAX	ACIHX	Difference
Max Drawdown Largest peak-to-trough decline	-47.97%	-24.00%	-23.97%
Max Drawdown (1Y) Largest decline over 1 year	-16.78%	-16.40%	-0.38%
Max Drawdown (3Y) Largest decline over 3 years	-23.45%	-24.00%	+0.55%
Max Drawdown (5Y) Largest decline over 5 years	-36.03%	—	—
Max Drawdown (10Y) Largest decline over 10 years	-36.03%	—	—
Current Drawdown Current decline from peak	-0.29%	-0.51%	+0.22%
Average Drawdown Average peak-to-trough decline	-7.44%	-4.89%	-2.55%
Ulcer Index Depth and duration of drawdowns from previous peaks	4.83%	4.87%	-0.04%

Volatility

VMGAX vs. ACIHX - Volatility Comparison

Vanguard Mega Cap Growth Index Fund Institutional Shares (VMGAX) has a higher volatility of 3.80% compared to American Century Growth Fund G Class (ACIHX) at 3.44%. This indicates that VMGAX'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

	VMGAX	ACIHX	Difference
Volatility (1M) Calculated over the trailing 1-month period	3.80%	3.44%	+0.36%
Volatility (6M) Calculated over the trailing 6-month period	12.39%	11.92%	+0.47%
Volatility (1Y) Calculated over the trailing 1-year period	16.23%	15.71%	+0.52%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	22.71%	21.05%	+1.66%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	21.90%	21.05%	+0.85%

VMGAX vs. ACIHX - Expense Ratio Comparison

VMGAX has a 0.06% expense ratio, which is higher than ACIHX's 0.01% expense ratio. However, both funds are considered low-cost compared to the broader market, where average expense ratios usually range from 0.3% to 0.9%.

Dividends

VMGAX vs. ACIHX - Dividend Comparison

VMGAX's dividend yield for the trailing twelve months is around 0.32%, less than ACIHX's 14.64% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
ACIHX American Century Growth Fund G Class	14.64%	15.95%	5.65%	4.61%	2.86%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%
VMGAX Vanguard Mega Cap Growth Index Fund Institutional Shares	0.32%	0.36%	0.44%	0.51%	0.71%	0.42%	0.65%	0.86%	1.13%	1.23%	1.53%	1.44%

Frequently Asked Questions

Can I hold both VMGAX and ACIHX in my portfolio?

With a correlation of 0.98, VMGAX 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, VMGAX or ACIHX?

VMGAX has higher volatility (3.80%) compared to ACIHX (3.44%). In terms of maximum drawdown, VMGAX dropped -47.97% vs ACIHX's -24.00%.

Which has better risk-adjusted returns?

VMGAX currently has the higher Sharpe Ratio (2.01 vs 1.83), 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.