AAMTX vs. PTDIX

Last updated Jun 4, 2026

AAMTX (American Funds 2055 Target Date Retirement Fund) and PTDIX (Principal LifeTime 2040 Fund) are both Target Retirement Date funds. Over the past 10 years, AAMTX returned 12.01%/yr vs 10.55%/yr for PTDIX. With a 0.97 correlation, they move nearly in lockstep. AAMTX charges 0.33%/yr vs 0.01%/yr for PTDIX.

Performance

AAMTX vs. PTDIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in American Funds 2055 Target Date Retirement Fund (AAMTX) and Principal LifeTime 2040 Fund (PTDIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, AAMTX achieves a 10.80% return, which is significantly higher than PTDIX's 7.80% return. Over the past 10 years, AAMTX has outperformed PTDIX with an annualized return of 12.01%, while PTDIX has yielded a comparatively lower 10.55% annualized return.

AAMTX

• 1D: 0.21%
• 1M: 4.84%
• YTD: 10.80%
• 6M: 11.49%
• 1Y: 25.89%
• 3Y*: 19.32%
• 5Y*: 9.84%
• 10Y*: 12.01%

PTDIX

• 1D: 0.34%
• 1M: 3.88%
• YTD: 7.80%
• 6M: 8.09%
• 1Y: 19.26%
• 3Y*: 17.13%
• 5Y*: 8.31%
• 10Y*: 10.55%

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

AAMTX vs. PTDIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
AAMTX American Funds 2055 Target Date Retirement Fund	10.80%	20.37%	15.16%	21.03%	-19.75%	16.94%	19.06%	24.60%	-5.95%	22.20%
PTDIX Principal LifeTime 2040 Fund	7.80%	15.59%	17.43%	18.33%	-18.13%	15.35%	16.04%	24.91%	-7.95%	20.69%

Correlation

The correlation between AAMTX and PTDIX 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	0.95
Correlation (5Y) Calculated over the trailing 5-year period	0.97
Correlation (10Y) Calculated over the trailing 10-year period	0.97
Correlation (All Time) Calculated using the full available price history since Feb 3, 2010	0.97

The correlation between AAMTX and PTDIX has been stable across timeframes, ranging from 0.95 to 0.97 - a consistent structural relationship.

Return for Risk

AAMTX vs. PTDIX — Risk / Return Rank

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

AAMTX

AAMTX Risk / Return Rank: 56
AAMTX Sharpe Ratio Rank: 57
AAMTX Sortino Ratio Rank: 54
AAMTX Omega Ratio Rank: 56
AAMTX Calmar Ratio Rank: 51
AAMTX Martin Ratio Rank: 63

PTDIX

PTDIX Risk / Return Rank: 50
PTDIX Sharpe Ratio Rank: 46
PTDIX Sortino Ratio Rank: 46
PTDIX Omega Ratio Rank: 47
PTDIX Calmar Ratio Rank: 49
PTDIX Martin Ratio Rank: 60

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.

AAMTX vs. PTDIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for American Funds 2055 Target Date Retirement Fund (AAMTX) and Principal LifeTime 2040 Fund (PTDIX). 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.

	AAMTX	PTDIX	Difference
Sharpe ratio Return per unit of total volatility	2.23	2.00	+0.23
Sortino ratio Return per unit of downside risk	3.12	2.84	+0.28
Omega ratio Gain probability vs. loss probability	1.41	1.37	+0.04
Calmar ratio Return relative to maximum drawdown	2.72	2.68	+0.04
Martin ratio Return relative to average drawdown	12.35	11.94	+0.41
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

AAMTX vs. PTDIX - Sharpe Ratio Comparison

The current AAMTX Sharpe Ratio is 2.23, which is comparable to the PTDIX Sharpe Ratio of 2.00. The chart below compares the historical Sharpe Ratios of AAMTX and PTDIX, 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

	AAMTX	PTDIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.23	2.00	+0.23
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.68	0.62	+0.06
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.80	0.77	+0.04
Sharpe Ratio (All Time) Calculated using the full available price history	0.77	0.48	+0.29

Drawdowns

AAMTX vs. PTDIX - Drawdown Comparison

The maximum AAMTX drawdown since its inception was -29.32%, smaller than the maximum PTDIX drawdown of -54.38%. Use the drawdown chart below to compare losses from any high point for AAMTX and PTDIX.

Drawdown Indicators

	AAMTX	PTDIX	Difference
Max Drawdown Largest peak-to-trough decline	-29.32%	-54.38%	+25.06%
Max Drawdown (1Y) Largest decline over 1 year	-9.71%	-7.32%	-2.39%
Max Drawdown (3Y) Largest decline over 3 years	-15.39%	-13.05%	-2.34%
Max Drawdown (5Y) Largest decline over 5 years	-27.34%	-25.43%	-1.91%
Max Drawdown (10Y) Largest decline over 10 years	-29.32%	-30.02%	+0.70%
Current Drawdown Current decline from peak	0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-4.28%	-7.49%	+3.21%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.14%	1.64%	+0.50%

Volatility

AAMTX vs. PTDIX - Volatility Comparison

American Funds 2055 Target Date Retirement Fund (AAMTX) has a higher volatility of 3.43% compared to Principal LifeTime 2040 Fund (PTDIX) at 2.89%. This indicates that AAMTX's price experiences larger fluctuations and is considered to be riskier than PTDIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	AAMTX	PTDIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	3.43%	2.89%	+0.54%
Volatility (6M) Calculated over the trailing 6-month period	9.52%	7.85%	+1.67%
Volatility (1Y) Calculated over the trailing 1-year period	11.87%	9.81%	+2.06%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	14.59%	13.49%	+1.10%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	15.03%	13.83%	+1.20%

AAMTX vs. PTDIX - Expense Ratio Comparison

AAMTX has a 0.33% expense ratio, which is higher than PTDIX's 0.01% expense ratio.

Dividends

AAMTX vs. PTDIX - Dividend Comparison

AAMTX's dividend yield for the trailing twelve months is around 5.14%, less than PTDIX's 9.09% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
AAMTX American Funds 2055 Target Date Retirement Fund	5.14%	5.70%	3.22%	2.22%	6.92%	4.15%	2.98%	3.92%	4.46%	2.18%	3.19%	4.06%
PTDIX Principal LifeTime 2040 Fund	9.09%	9.80%	12.28%	4.40%	8.61%	8.92%	6.01%	7.26%	9.28%	6.07%	4.86%	6.73%

Frequently Asked Questions

Can I hold both AAMTX and PTDIX in my portfolio?

With a correlation of 0.95, AAMTX and PTDIX 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, AAMTX or PTDIX?

AAMTX has higher volatility (3.43%) compared to PTDIX (2.89%). In terms of maximum drawdown, AAMTX dropped -29.32% vs PTDIX's -54.38%.

Which has better risk-adjusted returns?

AAMTX currently has the higher Sharpe Ratio (2.23 vs 2.00), 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.