RMAGX vs. GUSTX

Last updated Jun 4, 2026

RMAGX (American Funds Mortgage Fund Class R-6) and GUSTX (GMO U.S. Treasury Fund) are both Government Bonds funds. Over the past 10 years, RMAGX returned 1.60%/yr vs -13.74%/yr for GUSTX. At a 0.11 correlation, their price movements are largely independent. RMAGX charges 0.26%/yr vs 0.01%/yr for GUSTX.

Performance

RMAGX vs. GUSTX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in American Funds Mortgage Fund Class R-6 (RMAGX) and GMO U.S. Treasury Fund (GUSTX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, RMAGX achieves a -0.08% return, which is significantly lower than GUSTX's 1.46% return. Over the past 10 years, RMAGX has outperformed GUSTX with an annualized return of 1.60%, while GUSTX has yielded a comparatively lower -13.74% annualized return.

RMAGX

• 1D: 0.00%
• 1M: 0.25%
• YTD: -0.08%
• 6M: 0.20%
• 1Y: 5.75%
• 3Y*: 3.89%
• 5Y*: 0.48%
• 10Y*: 1.60%

GUSTX

• 1D: 0.00%
• 1M: 0.34%
• YTD: 1.46%
• 6M: 1.79%
• 1Y: 3.90%
• 3Y*: 3.18%
• 5Y*: 1.95%
• 10Y*: -13.74%

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

RMAGX vs. GUSTX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
RMAGX American Funds Mortgage Fund Class R-6	-0.08%	8.91%	1.01%	3.25%	-10.22%	-0.24%	7.02%	5.09%	0.86%	1.77%
GUSTX GMO U.S. Treasury Fund	1.46%	4.45%	2.21%	2.52%	-0.73%	-0.06%	0.89%	0.14%	-79.59%	0.43%

Correlation

The correlation between RMAGX and GUSTX is 0.34, which is low. Their price movements are largely independent, making them effective diversification partners.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.34
Correlation (3Y) Calculated over the trailing 3-year period	0.15
Correlation (5Y) Calculated over the trailing 5-year period	0.11
Correlation (10Y) Calculated over the trailing 10-year period	0.14
Correlation (All Time) Calculated using the full available price history since Jan 4, 2011	0.11

Over the past year, RMAGX and GUSTX have become more correlated (0.34) than their long-term average of 0.11, meaning their price movements have been converging.

Return for Risk

RMAGX vs. GUSTX — Risk / Return Rank

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

RMAGX

RMAGX Risk / Return Rank: 23
RMAGX Sharpe Ratio Rank: 22
RMAGX Sortino Ratio Rank: 24
RMAGX Omega Ratio Rank: 23
RMAGX Calmar Ratio Rank: 22
RMAGX Martin Ratio Rank: 21

GUSTX

GUSTX Risk / Return Rank: 99
GUSTX Sharpe Ratio Rank: 95
GUSTX Sortino Ratio Rank: 100
GUSTX Omega Ratio Rank: 100
GUSTX Calmar Ratio Rank: 100
GUSTX Martin Ratio Rank: 99

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.

RMAGX vs. GUSTX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for American Funds Mortgage Fund Class R-6 (RMAGX) and GMO U.S. Treasury Fund (GUSTX). 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.

	RMAGX	GUSTX	Difference
Sharpe ratio Return per unit of total volatility	1.35	3.34	-1.99
Sortino ratio Return per unit of downside risk	2.08	11.33	-9.25
Omega ratio Gain probability vs. loss probability	1.25	7.41	-6.16
Calmar ratio Return relative to maximum drawdown	1.71	20.36	-18.65
Martin ratio Return relative to average drawdown	5.52	57.94	-52.42
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

RMAGX vs. GUSTX - Sharpe Ratio Comparison

The current RMAGX Sharpe Ratio is 1.35, which is lower than the GUSTX Sharpe Ratio of 3.34. The chart below compares the historical Sharpe Ratios of RMAGX and GUSTX, 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

	RMAGX	GUSTX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.35	3.34	-1.99
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.08	1.14	-1.06
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.33	-0.54	+0.88
Sharpe Ratio (All Time) Calculated using the full available price history	0.51	-0.44	+0.95

Drawdowns

RMAGX vs. GUSTX - Drawdown Comparison

The maximum RMAGX drawdown since its inception was -15.93%, smaller than the maximum GUSTX drawdown of -79.98%. Use the drawdown chart below to compare losses from any high point for RMAGX and GUSTX.

Drawdown Indicators

	RMAGX	GUSTX	Difference
Max Drawdown Largest peak-to-trough decline	-15.93%	-79.98%	+64.05%
Max Drawdown (1Y) Largest decline over 1 year	-3.37%	-0.20%	-3.17%
Max Drawdown (3Y) Largest decline over 3 years	-7.29%	-1.19%	-6.10%
Max Drawdown (5Y) Largest decline over 5 years	-15.93%	-1.19%	-14.74%
Max Drawdown (10Y) Largest decline over 10 years	-15.93%	-79.98%	+64.05%
Current Drawdown Current decline from peak	-1.79%	-77.68%	+75.89%
Average Drawdown Average peak-to-trough decline	-2.34%	-36.04%	+33.70%
Ulcer Index Depth and duration of drawdowns from previous peaks	1.04%	0.07%	+0.97%

Volatility

RMAGX vs. GUSTX - Volatility Comparison

American Funds Mortgage Fund Class R-6 (RMAGX) has a higher volatility of 1.64% compared to GMO U.S. Treasury Fund (GUSTX) at 0.34%. This indicates that RMAGX's price experiences larger fluctuations and is considered to be riskier than GUSTX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	RMAGX	GUSTX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.64%	0.34%	+1.30%
Volatility (6M) Calculated over the trailing 6-month period	3.08%	0.87%	+2.21%
Volatility (1Y) Calculated over the trailing 1-year period	4.28%	1.22%	+3.06%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	6.41%	1.75%	+4.66%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	4.84%	25.45%	-20.61%

RMAGX vs. GUSTX - Expense Ratio Comparison

RMAGX has a 0.26% expense ratio, which is higher than GUSTX's 0.01% 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

RMAGX vs. GUSTX - Dividend Comparison

RMAGX's dividend yield for the trailing twelve months is around 4.60%, more than GUSTX's 3.82% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
GUSTX GMO U.S. Treasury Fund	3.82%	4.15%	1.98%	2.28%	0.26%	0.14%	0.09%	0.14%	8.96%	0.50%	0.05%	0.04%
RMAGX American Funds Mortgage Fund Class R-6	4.60%	4.60%	4.94%	3.61%	1.70%	0.74%	4.79%	3.27%	2.14%	2.07%	2.69%	2.82%

Frequently Asked Questions

Can I hold both RMAGX and GUSTX in my portfolio?

RMAGX and GUSTX have a correlation of 0.34, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, RMAGX or GUSTX?

RMAGX has higher volatility (1.64%) compared to GUSTX (0.34%). In terms of maximum drawdown, RMAGX dropped -15.93% vs GUSTX's -79.98%.

Which has better risk-adjusted returns?

GUSTX currently has the higher Sharpe Ratio (3.34 vs 1.35), 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.