MARMX vs. TDIFX

Last updated Jun 4, 2026

MARMX (Mutual of America Retirement Income Fund) and TDIFX (Dimensional Retirement Income Fund) are both Target Retirement Date funds. Over the past 5 years, MARMX returned 3.23%/yr vs 5.13%/yr for TDIFX. A 0.74 correlation means they provide meaningful diversification when combined. MARMX charges 0.13%/yr vs 0.06%/yr for TDIFX.

Performance

MARMX vs. TDIFX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Mutual of America Retirement Income Fund (MARMX) and Dimensional Retirement Income Fund (TDIFX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

The year-to-date returns for both investments are quite close, with MARMX having a 3.75% return and TDIFX slightly higher at 3.88%.

MARMX

• 1D: 0.08%
• 1M: 1.93%
• YTD: 3.75%
• 6M: 3.95%
• 1Y: 11.47%
• 3Y*: 8.00%
• 5Y*: 3.23%
• 10Y*: —

TDIFX

• 1D: 0.08%
• 1M: 1.22%
• YTD: 3.88%
• 6M: 3.88%
• 1Y: 8.34%
• 3Y*: 7.14%
• 5Y*: 5.13%
• 10Y*: 5.12%

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

MARMX vs. TDIFX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020
MARMX Mutual of America Retirement Income Fund	3.75%	10.54%	5.88%	7.79%	-11.40%	3.49%	890.98%
TDIFX Dimensional Retirement Income Fund	3.88%	7.22%	6.21%	7.76%	-9.37%	14.53%	7.61%

Correlation

The correlation between MARMX and TDIFX is 0.71, which is moderate. They share some common price drivers but move independently often enough to provide real diversification benefit when combined.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.71
Correlation (3Y) Calculated over the trailing 3-year period	0.82
Correlation (5Y) Calculated over the trailing 5-year period	0.76
Correlation (All Time) Calculated using the full available price history since Jun 29, 2020	0.74

The correlation between MARMX and TDIFX shifts across timeframes, from 0.71 (1 year) to 0.82 (3 years), reflecting how their relationship changes across market environments.

Return for Risk

MARMX vs. TDIFX — Risk / Return Rank

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

MARMX

MARMX Risk / Return Rank: 77
MARMX Sharpe Ratio Rank: 76
MARMX Sortino Ratio Rank: 82
MARMX Omega Ratio Rank: 75
MARMX Calmar Ratio Rank: 72
MARMX Martin Ratio Rank: 80

TDIFX

TDIFX Risk / Return Rank: 83
TDIFX Sharpe Ratio Rank: 86
TDIFX Sortino Ratio Rank: 85
TDIFX Omega Ratio Rank: 84
TDIFX Calmar Ratio Rank: 78
TDIFX Martin Ratio Rank: 82

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.

MARMX vs. TDIFX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Mutual of America Retirement Income Fund (MARMX) and Dimensional Retirement Income Fund (TDIFX). 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.

	MARMX	TDIFX	Difference
Sharpe ratio: Return per unit of total volatility	2.54	2.79	-0.24
Sortino ratio: Return per unit of downside risk	3.94	4.05	-0.12
Omega ratio: Gain probability vs. loss probability	1.49	1.57	-0.07
Calmar ratio: Return relative to maximum drawdown	3.29	3.56	-0.27
Martin ratio: Return relative to average drawdown	15.05	15.52	-0.47
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

MARMX vs. TDIFX - Sharpe Ratio Comparison

The current MARMX Sharpe Ratio is 2.54, which is comparable to the TDIFX Sharpe Ratio of 2.79. The chart below compares the historical Sharpe Ratios of MARMX and TDIFX, 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

	MARMX	TDIFX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.54	2.79	-0.24
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.48	0.89	-0.41
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	—	1.02	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.15	1.06	-0.91

Drawdowns

MARMX vs. TDIFX - Drawdown Comparison

The maximum MARMX drawdown since its inception was -16.21%, which is greater than TDIFX's maximum drawdown of -12.21%. Use the drawdown chart below to compare losses from any high point for MARMX and TDIFX.

Drawdown Indicators

	MARMX	TDIFX	Difference
Max Drawdown Largest peak-to-trough decline	-16.21%	-12.21%	-4.00%
Max Drawdown (1Y) Largest decline over 1 year	-3.92%	-2.61%	-1.31%
Max Drawdown (3Y) Largest decline over 3 years	-5.64%	-3.51%	-2.13%
Max Drawdown (5Y) Largest decline over 5 years	-15.94%	-12.21%	-3.73%
Max Drawdown (10Y) Largest decline over 10 years	—	-12.21%	—
Current Drawdown Current decline from peak	0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-4.28%	-1.75%	-2.53%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.82%	0.58%	+0.24%

Volatility

MARMX vs. TDIFX - Volatility Comparison

Mutual of America Retirement Income Fund (MARMX) has a higher volatility of 1.76% compared to Dimensional Retirement Income Fund (TDIFX) at 1.01%. This indicates that MARMX's price experiences larger fluctuations and is considered to be riskier than TDIFX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	MARMX	TDIFX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.76%	1.01%	+0.75%
Volatility (6M) Calculated over the trailing 6-month period	4.13%	2.49%	+1.64%
Volatility (1Y) Calculated over the trailing 1-year period	5.08%	3.33%	+1.75%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	7.53%	5.89%	+1.64%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	393.36%	5.06%	+388.30%

MARMX vs. TDIFX - Expense Ratio Comparison

MARMX has a 0.13% expense ratio, which is higher than TDIFX's 0.06% 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

MARMX vs. TDIFX - Dividend Comparison

MARMX's dividend yield for the trailing twelve months is around 4.16%, more than TDIFX's 1.99% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016
MARMX Mutual of America Retirement Income Fund	4.16%	4.32%	4.16%	1.55%	5.73%	2.03%	0.00%	0.00%	0.00%	0.00%	0.00%
TDIFX Dimensional Retirement Income Fund	1.99%	1.77%	3.11%	3.09%	4.66%	9.39%	1.39%	1.98%	2.11%	0.98%	0.89%

Frequently Asked Questions

Can I hold both MARMX and TDIFX in my portfolio?

MARMX and TDIFX have a correlation of 0.71, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, MARMX or TDIFX?

MARMX has higher volatility (1.76%) compared to TDIFX (1.01%). In terms of maximum drawdown, MARMX dropped -16.21% vs TDIFX's -12.21%.

Which has better risk-adjusted returns?

TDIFX currently has the higher Sharpe Ratio (2.79 vs 2.54), 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.