TWUIX vs. ACFOX

Last updated Jul 25, 2026

TWUIX (American Century Ultra Fund I Class) and ACFOX (American Century Investments Focused Dynamic Growth Fund) are both Large Cap Growth Equities funds from American Century. Over the past 10 years, TWUIX returned 17.10%/yr vs 17.70%/yr for ACFOX. Their correlation of 0.93 suggests significant overlap in exposure. TWUIX charges 0.67%/yr vs 0.85%/yr for ACFOX.

Performance

TWUIX vs. ACFOX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in American Century Ultra Fund I Class (TWUIX) and American Century Investments Focused Dynamic Growth Fund (ACFOX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, TWUIX achieves a 0.54% return, which is significantly higher than ACFOX's -2.34% return. Both investments have delivered pretty close results over the past 10 years, with TWUIX having a 17.10% annualized return and ACFOX not far ahead at 17.70%.

TWUIX

• 1D: -2.19%
• 1M: -1.08%
• 6M: 0.81%
• YTD: 0.54%
• 1Y: 8.96%
• 3Y*: 16.60%
• 5Y*: 8.30%
• 10Y*: 17.10%
• ALL TIME*: 9.87%

ACFOX

• 1D: -3.08%
• 1M: -3.19%
• 6M: -3.49%
• YTD: -2.34%
• 1Y: 9.66%
• 3Y*: 20.86%
• 5Y*: 6.77%
• 10Y*: 17.70%
• ALL TIME*: 11.96%

*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
TWUIX American Century Ultra Fund I Class	$0.00	$0.00	$0.00

TWUIX vs. ACFOX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
TWUIX American Century Ultra Fund I Class	0.54%	12.88%	29.80%	43.63%	-32.25%	23.70%	50.09%	34.90%	0.90%	31.63%
ACFOX American Century Investments Focused Dynamic Growth Fund	-2.34%	20.51%	43.30%	35.66%	-36.32%	7.08%	73.31%	32.30%	6.51%	34.55%

Correlation

The correlation between TWUIX and ACFOX is 0.95 - 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	0.95
Correlation (3Y) Calculated over the trailing 3-year period	0.96
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 May 31, 2006	0.93

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

Return for Risk

TWUIX vs. ACFOX — Risk / Return Rank

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

TWUIX

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

ACFOX

ACFOX Risk / Return Rank: 10
ACFOX Sharpe Ratio Rank: 10
ACFOX Sortino Ratio Rank: 10
ACFOX Omega Ratio Rank: 10
ACFOX Calmar Ratio Rank: 10
ACFOX Martin Ratio Rank: 11

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.

TWUIX vs. ACFOX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for American Century Ultra Fund I Class (TWUIX) and American Century Investments Focused Dynamic Growth Fund (ACFOX). 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.

	TWUIX	ACFOX	Difference
Sharpe ratio: Return per unit of total volatility	0.50	0.44	+0.06
Sortino ratio: Return per unit of downside risk	0.80	0.74	+0.06
Omega ratio: Gain probability vs. loss probability	1.10	1.09	+0.01
Calmar ratio: Return relative to maximum drawdown	0.57	0.56	+0.01
Martin ratio: Return relative to average drawdown	1.82	1.75	+0.07

TWUIX vs. ACFOX - Sharpe Ratio Comparison

The current TWUIX Sharpe Ratio is 0.50, which is comparable to the ACFOX Sharpe Ratio of 0.44. The chart below compares the historical Sharpe Ratios of TWUIX and ACFOX, 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

TWUIX vs. ACFOX - Drawdown Comparison

The maximum TWUIX drawdown since its inception was -61.41%, roughly equal to the maximum ACFOX drawdown of -58.92%. Use the drawdown chart below to compare losses from any high point for TWUIX and ACFOX.

Drawdown Indicators

	TWUIX	ACFOX	Difference
Max Drawdown Largest peak-to-trough decline	-61.41%	-58.92%	-2.49%
Max Drawdown (1Y) Largest decline over 1 year	-15.64%	-16.52%	+0.88%
Max Drawdown (3Y) Largest decline over 3 years	-24.82%	-27.03%	+2.21%
Max Drawdown (5Y) Largest decline over 5 years	-35.12%	-43.77%	+8.65%
Max Drawdown (10Y) Largest decline over 10 years	-35.12%	-43.77%	+8.65%
Current Drawdown Current decline from peak	-8.76%	-11.59%	+2.83%
Average Drawdown Average peak-to-trough decline	-18.08%	-14.65%	-3.43%
Ulcer Index Depth and duration of drawdowns from previous peaks	4.93%	5.30%	-0.37%

Volatility

TWUIX vs. ACFOX - Volatility Comparison

The current volatility for American Century Ultra Fund I Class (TWUIX) is 5.49%, while American Century Investments Focused Dynamic Growth Fund (ACFOX) has a volatility of 6.86%. This indicates that TWUIX experiences smaller price fluctuations and is considered to be less risky than ACFOX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	TWUIX	ACFOX	Difference
Volatility (1M) Calculated over the trailing 1-month period	5.49%	6.86%	-1.37%
Volatility (6M) Calculated over the trailing 6-month period	14.04%	17.00%	-2.96%
Volatility (1Y) Calculated over the trailing 1-year period	17.89%	20.97%	-3.08%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	22.78%	25.62%	-2.84%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	22.15%	23.94%	-1.79%

TWUIX vs. ACFOX - Expense Ratio Comparison

TWUIX has a 0.67% expense ratio, which is lower than ACFOX's 0.85% expense ratio.

Dividends

TWUIX vs. ACFOX - Dividend Comparison

TWUIX's dividend yield for the trailing twelve months is around 10.70%, more than ACFOX's 7.74% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
ACFOX American Century Investments Focused Dynamic Growth Fund	7.74%	7.56%	0.00%	0.00%	0.00%	2.48%	0.62%	0.00%	0.00%	0.00%	1.15%	1.33%
TWUIX American Century Ultra Fund I Class	10.70%	10.76%	3.36%	5.73%	7.03%	6.46%	2.68%	4.10%	7.94%	5.66%	4.44%	5.06%

Frequently Asked Questions

Can I hold both TWUIX and ACFOX in my portfolio?

With a correlation of 0.95, TWUIX and ACFOX 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, TWUIX or ACFOX?

ACFOX has higher volatility (6.86%) compared to TWUIX (5.49%). In terms of maximum drawdown, TWUIX dropped -61.41% vs ACFOX's -58.92%.

Which has better risk-adjusted returns?

TWUIX currently has the higher Sharpe Ratio (0.50 vs 0.44), 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.