ACFOX vs. VMGAX

Last updated Aug 4, 2026

ACFOX (American Century Investments Focused Dynamic Growth Fund) and VMGAX (Vanguard Mega Cap Growth Index Fund Institutional Shares) are both Large Cap Growth Equities funds. Over the past 10 years, ACFOX returned 17.66%/yr vs 18.27%/yr for VMGAX. Their correlation of 0.92 means they have usually moved in the same direction. ACFOX charges 0.85%/yr vs 0.05%/yr for VMGAX.

Performance

ACFOX vs. VMGAX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in American Century Investments Focused Dynamic Growth Fund (ACFOX) and Vanguard Mega Cap Growth Index Fund Institutional Shares (VMGAX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, ACFOX achieves a -0.75% return, which is significantly lower than VMGAX's 4.77% return. Both investments have delivered pretty close results over the past 10 years, with ACFOX having a 17.66% annualized return and VMGAX not far ahead at 18.27%.

ACFOX

• 1D: 2.72%
• 1M: -4.43%
• 6M: 0.01%
• YTD: -0.75%
• 1Y: 13.02%
• 3Y*: 21.13%
• 5Y*: 7.41%
• 10Y*: 17.66%
• ALL TIME*: 12.04%

VMGAX

• 1D: 1.14%
• 1M: -0.93%
• 6M: 6.38%
• YTD: 4.77%
• 1Y: 16.42%
• 3Y*: 21.81%
• 5Y*: 13.07%
• 10Y*: 18.27%
• ALL TIME*: 13.45%

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

Liquidity Comparison

Position	Avg. Volume Value (2W)	Avg. Volume Value (1M)	Avg. Volume Value (3M)
ACFOX American Century Investments Focused Dynamic Growth Fund	$0.00	$0.00	$0.00
VMGAX Vanguard Mega Cap Growth Index Fund Institutional Shares	$0.00	$0.00	$0.00

ACFOX vs. VMGAX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
ACFOX American Century Investments Focused Dynamic Growth Fund	-0.75%	20.51%	43.30%	35.66%	-36.32%	7.08%	73.31%	32.30%	6.51%	34.55%
VMGAX Vanguard Mega Cap Growth Index Fund Institutional Shares	4.77%	20.73%	32.98%	51.57%	-33.55%	28.50%	41.02%	37.54%	-2.86%	29.49%

Correlation

The correlation between ACFOX and VMGAX is 0.94, meaning they have usually moved in the same direction, including during past declines.

	Correlation
Correlation (1Y) Focuses on recent behavior, but can change the most.	0.94
Correlation (3Y) Balances recent behavior with more history.	0.94
Correlation (5Y) Shows whether the relationship held over a longer period.	0.95
Correlation (10Y) Provides a long-term view across more market conditions.	0.92
Correlation (All Time) Calculated using the full available price history since Dec 27, 2007	0.92

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

Return for Risk

ACFOX vs. VMGAX — Risk / Return Rank

Compare historical risk-adjusted metric ranks over the past 12 months.

ACFOX

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

VMGAX

VMGAX Risk / Return Rank: 18
VMGAX Sharpe Ratio Rank: 19
VMGAX Sortino Ratio Rank: 19
VMGAX Omega Ratio Rank: 18
VMGAX Calmar Ratio Rank: 15
VMGAX Martin Ratio Rank: 17

The rank (0–100) uses a weighted average of the Sharpe, Sortino, Omega, Calmar, and Martin percentile ranks for the trailing 12 months. Higher means stronger historical risk-adjusted performance within the peer group.

ACFOX vs. VMGAX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for American Century Investments Focused Dynamic Growth Fund (ACFOX) and Vanguard Mega Cap Growth Index Fund Institutional Shares (VMGAX). 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.

	ACFOX	VMGAX	Difference
Sharpe ratio: Return per unit of total volatility	0.50	0.76	-0.26
Sortino ratio: Return per unit of downside risk	0.82	1.16	-0.34
Omega ratio: Gain probability vs. loss probability	1.10	1.14	-0.04
Calmar ratio: Return relative to maximum drawdown	0.65	0.83	-0.19
Martin ratio: Return relative to average drawdown	1.89	2.60	-0.71

ACFOX vs. VMGAX - Sharpe Ratio Comparison

The current ACFOX Sharpe Ratio is 0.50, which is lower than the VMGAX Sharpe Ratio of 0.76. The chart below compares the historical Sharpe Ratios of ACFOX and VMGAX, 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

ACFOX vs. VMGAX - Drawdown Comparison

The maximum ACFOX drawdown since its inception was -58.92%, which is greater than VMGAX's maximum drawdown of -47.97%. Use the drawdown chart below to compare losses from any high point for ACFOX and VMGAX.

Drawdown Indicators

	ACFOX	VMGAX	Difference
Max Drawdown Largest peak-to-trough decline	-58.92%	-47.97%	-10.95%
Max Drawdown (1Y) Largest decline over 1 year	-16.52%	-16.78%	+0.26%
Max Drawdown (3Y) Largest decline over 3 years	-27.03%	-23.45%	-3.58%
Max Drawdown (5Y) Largest decline over 5 years	-43.77%	-36.03%	-7.74%
Max Drawdown (10Y) Largest decline over 10 years	-43.77%	-36.03%	-7.74%
Current Drawdown Current decline from peak	-10.14%	-6.12%	-4.02%
Average Drawdown Average peak-to-trough decline	-14.65%	-7.42%	-7.23%
Ulcer Index Depth and duration of drawdowns from previous peaks	5.64%	5.35%	+0.29%

Volatility

ACFOX vs. VMGAX - Volatility Comparison

American Century Investments Focused Dynamic Growth Fund (ACFOX) has a higher volatility of 7.15% compared to Vanguard Mega Cap Growth Index Fund Institutional Shares (VMGAX) at 5.83%. This indicates that ACFOX's price experiences larger fluctuations and is considered to be riskier than VMGAX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	ACFOX	VMGAX	Difference
Volatility (1M) Calculated over the trailing 1-month period	7.15%	5.83%	+1.32%
Volatility (6M) Calculated over the trailing 6-month period	17.40%	14.69%	+2.71%
Volatility (1Y) Calculated over the trailing 1-year period	21.33%	18.26%	+3.07%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	25.67%	23.00%	+2.67%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	23.97%	22.02%	+1.95%

ACFOX vs. VMGAX - Expense Ratio Comparison

ACFOX has a 0.85% expense ratio, which is higher than VMGAX's 0.05% expense ratio.

Dividends

ACFOX vs. VMGAX - Dividend Comparison

ACFOX's dividend yield for the trailing twelve months is around 7.61%, more than VMGAX's 0.35% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
ACFOX American Century Investments Focused Dynamic Growth Fund	7.61%	7.56%	0.00%	0.00%	0.00%	2.48%	0.62%	0.00%	0.00%	0.00%	1.15%	1.33%
VMGAX Vanguard Mega Cap Growth Index Fund Institutional Shares	0.35%	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 ACFOX and VMGAX in my portfolio?

With a correlation of 0.94, ACFOX and VMGAX 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, ACFOX or VMGAX?

ACFOX has higher volatility (7.15%) compared to VMGAX (5.83%). In terms of maximum drawdown, ACFOX dropped -58.92% vs VMGAX's -47.97%.

Which has better risk-adjusted returns?

VMGAX currently has the higher Sharpe Ratio (0.76 vs 0.50), 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.