AMUSX vs. LTUSX

Last updated Jun 4, 2026

AMUSX (American Funds U.S. Government Securities Fund) and LTUSX (Thornburg Limited Term U.S. Government Fund) are both Government Bonds funds. Over the past 10 years, AMUSX returned 1.14%/yr vs 1.02%/yr for LTUSX. Their correlation of 0.82 suggests significant overlap in exposure. AMUSX charges 0.61%/yr vs 0.92%/yr for LTUSX.

Performance

AMUSX vs. LTUSX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in American Funds U.S. Government Securities Fund (AMUSX) and Thornburg Limited Term U.S. Government Fund (LTUSX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, AMUSX achieves a -0.35% return, which is significantly lower than LTUSX's 0.47% return. Over the past 10 years, AMUSX has outperformed LTUSX with an annualized return of 1.14%, while LTUSX has yielded a comparatively lower 1.02% annualized return.

AMUSX

• 1D: 0.00%
• 1M: 0.28%
• YTD: -0.35%
• 6M: -0.26%
• 1Y: 4.29%
• 3Y*: 3.14%
• 5Y*: -0.13%
• 10Y*: 1.14%

LTUSX

• 1D: 0.00%
• 1M: 0.17%
• YTD: 0.47%
• 6M: 0.45%
• 1Y: 4.63%
• 3Y*: 3.65%
• 5Y*: 0.68%
• 10Y*: 1.02%

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

AMUSX vs. LTUSX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
AMUSX American Funds U.S. Government Securities Fund	-0.35%	7.55%	0.63%	2.79%	-11.50%	-0.84%	9.44%	5.03%	0.64%	1.54%
LTUSX Thornburg Limited Term U.S. Government Fund	0.47%	6.40%	2.40%	3.40%	-8.06%	-1.82%	3.77%	3.61%	0.98%	0.60%

Correlation

The correlation between AMUSX and LTUSX is 0.92, indicating a strong positive relationship between their price movements. Combining them offers limited diversification - they tend to fall together during downturns.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.92
Correlation (3Y) Calculated over the trailing 3-year period	0.94
Correlation (5Y) Calculated over the trailing 5-year period	0.95
Correlation (10Y) Calculated over the trailing 10-year period	0.91
Correlation (All Time) Calculated using the full available price history since Nov 17, 1987	0.82

The correlation between AMUSX and LTUSX shifts across timeframes, from 0.82 (all time) to 0.94 (5 years), reflecting how their relationship changes across market environments.

Return for Risk

AMUSX vs. LTUSX — Risk / Return Rank

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

AMUSX

AMUSX Risk / Return Rank: 14
AMUSX Sharpe Ratio Rank: 14
AMUSX Sortino Ratio Rank: 15
AMUSX Omega Ratio Rank: 14
AMUSX Calmar Ratio Rank: 13
AMUSX Martin Ratio Rank: 14

LTUSX

LTUSX Risk / Return Rank: 27
LTUSX Sharpe Ratio Rank: 28
LTUSX Sortino Ratio Rank: 30
LTUSX Omega Ratio Rank: 28
LTUSX Calmar Ratio Rank: 27
LTUSX Martin Ratio Rank: 23

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.

AMUSX vs. LTUSX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for American Funds U.S. Government Securities Fund (AMUSX) and Thornburg Limited Term U.S. Government Fund (LTUSX). 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.

	AMUSX	LTUSX	Difference
Sharpe ratio: Return per unit of total volatility	1.04	1.53	-0.49
Sortino ratio: Return per unit of downside risk	1.58	2.28	-0.70
Omega ratio: Gain probability vs. loss probability	1.19	1.28	-0.09
Calmar ratio: Return relative to maximum drawdown	1.26	1.94	-0.67
Martin ratio: Return relative to average drawdown	3.97	5.84	-1.87
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

AMUSX vs. LTUSX - Sharpe Ratio Comparison

The current AMUSX Sharpe Ratio is 1.04, which is lower than the LTUSX Sharpe Ratio of 1.53. The chart below compares the historical Sharpe Ratios of AMUSX and LTUSX, 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

	AMUSX	LTUSX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.04	1.53	-0.49
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	-0.02	0.17	-0.19
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.24	0.33	-0.10
Sharpe Ratio (All Time) Calculated using the full available price history	0.83	1.15	-0.31

Drawdowns

AMUSX vs. LTUSX - Drawdown Comparison

The maximum AMUSX drawdown since its inception was -17.48%, which is greater than LTUSX's maximum drawdown of -12.34%. Use the drawdown chart below to compare losses from any high point for AMUSX and LTUSX.

Drawdown Indicators

	AMUSX	LTUSX	Difference
Max Drawdown Largest peak-to-trough decline	-17.48%	-12.34%	-5.14%
Max Drawdown (1Y) Largest decline over 1 year	-3.35%	-2.31%	-1.04%
Max Drawdown (3Y) Largest decline over 3 years	-6.50%	-3.69%	-2.81%
Max Drawdown (5Y) Largest decline over 5 years	-16.84%	-11.69%	-5.15%
Max Drawdown (10Y) Largest decline over 10 years	-17.48%	-12.34%	-5.14%
Current Drawdown Current decline from peak	-3.24%	-1.50%	-1.74%
Average Drawdown Average peak-to-trough decline	-2.75%	-1.40%	-1.35%
Ulcer Index Depth and duration of drawdowns from previous peaks	1.06%	0.76%	+0.30%

Volatility

AMUSX vs. LTUSX - Volatility Comparison

American Funds U.S. Government Securities Fund (AMUSX) has a higher volatility of 1.54% compared to Thornburg Limited Term U.S. Government Fund (LTUSX) at 0.95%. This indicates that AMUSX's price experiences larger fluctuations and is considered to be riskier than LTUSX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	AMUSX	LTUSX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.54%	0.95%	+0.59%
Volatility (6M) Calculated over the trailing 6-month period	2.85%	2.04%	+0.81%
Volatility (1Y) Calculated over the trailing 1-year period	4.06%	2.93%	+1.13%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	6.06%	4.02%	+2.04%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	4.86%	3.08%	+1.78%

AMUSX vs. LTUSX - Expense Ratio Comparison

AMUSX has a 0.61% expense ratio, which is lower than LTUSX's 0.92% expense ratio.

Dividends

AMUSX vs. LTUSX - Dividend Comparison

AMUSX's dividend yield for the trailing twelve months is around 4.00%, more than LTUSX's 2.63% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
AMUSX American Funds U.S. Government Securities Fund	4.00%	3.97%	4.19%	3.44%	2.01%	1.05%	4.92%	2.79%	1.72%	1.32%	2.30%	2.84%
LTUSX Thornburg Limited Term U.S. Government Fund	2.63%	2.69%	2.62%	1.89%	1.63%	1.21%	1.35%	1.77%	1.90%	1.45%	2.52%	1.50%

Frequently Asked Questions

Can I hold both AMUSX and LTUSX in my portfolio?

With a correlation of 0.92, AMUSX and LTUSX 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, AMUSX or LTUSX?

AMUSX has higher volatility (1.54%) compared to LTUSX (0.95%). In terms of maximum drawdown, AMUSX dropped -17.48% vs LTUSX's -12.34%.

Which has better risk-adjusted returns?

LTUSX currently has the higher Sharpe Ratio (1.53 vs 1.04), 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.