AULDX vs. AMRGX

Last updated Apr 1, 2026

Compare and contrast key facts about American Century Ultra Fund Class R6 (AULDX) and American Growth Fund Series One (AMRGX).

AULDX is an actively managed fund by American Century. It was launched on Jul 26, 2013. AMRGX is managed by American Growth. It was launched on Jul 31, 1958.

Performance

AULDX vs. AMRGX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in American Century Ultra Fund Class R6 (AULDX) and American Growth Fund Series One (AMRGX). The values are adjusted to include any dividend payments, if applicable.

AULDX vs. AMRGX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
AULDX American Century Ultra Fund Class R6	-12.21%	13.05%	29.99%	43.86%	-32.15%	23.89%	50.31%	35.23%	1.04%	32.36%
AMRGX American Growth Fund Series One	-1.31%	11.18%	16.61%	24.38%	-19.93%	15.64%	18.65%	36.73%	-9.07%	13.37%

Returns By Period

In the year-to-date period, AULDX achieves a -12.21% return, which is significantly lower than AMRGX's -1.31% return. Over the past 10 years, AULDX has outperformed AMRGX with an annualized return of 16.09%, while AMRGX has yielded a comparatively lower 10.41% annualized return.

AULDX

• 1D: -0.65%
• 1M: -8.77%
• YTD: -12.21%
• 6M: -10.72%
• 1Y: 11.88%
• 3Y*: 16.86%
• 5Y*: 9.28%
• 10Y*: 16.09%

AMRGX

• 1D: -1.60%
• 1M: -10.92%
• YTD: -1.31%
• 6M: 7.51%
• 1Y: 16.26%
• 3Y*: 14.01%
• 5Y*: 7.34%
• 10Y*: 10.41%

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

AULDX vs. AMRGX - Expense Ratio Comparison

AULDX has a 0.52% expense ratio, which is lower than AMRGX's 4.07% expense ratio.

AMRGX

American Growth Fund Series One

AULDX

American Century Ultra Fund Class R6

Return for Risk

AULDX vs. AMRGX — Risk / Return Rank

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

AULDX

AULDX Risk / Return Rank: 19
AULDX Sharpe Ratio Rank: 19
AULDX Sortino Ratio Rank: 21
AULDX Omega Ratio Rank: 20
AULDX Calmar Ratio Rank: 18
AULDX Martin Ratio Rank: 18

AMRGX

AMRGX Risk / Return Rank: 32
AMRGX Sharpe Ratio Rank: 26
AMRGX Sortino Ratio Rank: 33
AMRGX Omega Ratio Rank: 45
AMRGX Calmar Ratio Rank: 37
AMRGX Martin Ratio Rank: 22

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.

AULDX vs. AMRGX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for American Century Ultra Fund Class R6 (AULDX) and American Growth Fund Series One (AMRGX). 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.

	AULDX	AMRGX	Difference
Sharpe ratio Return per unit of total volatility	0.51	0.62	-0.10
Sortino ratio Return per unit of downside risk	0.91	1.12	-0.21
Omega ratio Gain probability vs. loss probability	1.12	1.19	-0.07
Calmar ratio Return relative to maximum drawdown	0.56	0.99	-0.43
Martin ratio Return relative to average drawdown	1.98	2.37	-0.39
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

AULDX vs. AMRGX - Sharpe Ratio Comparison

The current AULDX Sharpe Ratio is 0.51, which is comparable to the AMRGX Sharpe Ratio of 0.62. The chart below compares the historical Sharpe Ratios of AULDX and AMRGX, offering insights into how both investments have performed under varying market conditions. These values are calculated using daily returns over the previous 12 months.

Sharpe Ratios by Period

	AULDX	AMRGX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	0.51	0.62	-0.10
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.41	0.34	+0.08
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.73	0.49	+0.24
Sharpe Ratio (All Time) Calculated using the full available price history	0.69	0.10	+0.59

Correlation

The correlation between AULDX and AMRGX is 0.84, which is considered to be high. That indicates a strong positive relationship between their price movements. Having highly-correlated positions in a portfolio may signal a lack of diversification, potentially leading to increased risk during market downturns.

Dividends

AULDX vs. AMRGX - Dividend Comparison

AULDX's dividend yield for the trailing twelve months is around 12.07%, less than AMRGX's 18.06% yield.

	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
AULDX American Century Ultra Fund Class R6	12.07%	10.60%	3.32%	5.68%	6.97%	6.42%	2.67%	4.18%	7.94%	6.19%	4.45%	5.06%
AMRGX American Growth Fund Series One	18.06%	17.82%	12.39%	8.17%	7.77%	12.21%	2.36%	0.00%	0.00%	0.00%	0.00%	0.00%

Drawdowns

AULDX vs. AMRGX - Drawdown Comparison

The maximum AULDX drawdown since its inception was -35.03%, smaller than the maximum AMRGX drawdown of -80.32%. Use the drawdown chart below to compare losses from any high point for AULDX and AMRGX.

Drawdown Indicators

	AULDX	AMRGX	Difference
Max Drawdown Largest peak-to-trough decline	-35.03%	-80.32%	+45.29%
Max Drawdown (1Y) Largest decline over 1 year	-15.60%	-13.98%	-1.62%
Max Drawdown (5Y) Largest decline over 5 years	-35.03%	-35.42%	+0.39%
Max Drawdown (10Y) Largest decline over 10 years	-35.03%	-35.42%	+0.39%
Current Drawdown Current decline from peak	-15.60%	-13.98%	-1.62%
Average Drawdown Average peak-to-trough decline	-6.23%	-40.45%	+34.22%
Ulcer Index Depth and duration of drawdowns from previous peaks	4.38%	5.82%	-1.44%

Volatility

AULDX vs. AMRGX - Volatility Comparison

The current volatility for American Century Ultra Fund Class R6 (AULDX) is 5.77%, while American Growth Fund Series One (AMRGX) has a volatility of 6.18%. This indicates that AULDX experiences smaller price fluctuations and is considered to be less risky than AMRGX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	AULDX	AMRGX	Difference
Volatility (1M) Calculated over the trailing 1-month period	5.77%	6.18%	-0.41%
Volatility (6M) Calculated over the trailing 6-month period	12.65%	23.49%	-10.84%
Volatility (1Y) Calculated over the trailing 1-year period	23.09%	28.26%	-5.17%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	22.54%	21.84%	+0.70%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	22.00%	21.30%	+0.70%