RFNBX vs. AHMFX

Last updated Jun 3, 2026

RFNBX (American Funds Fundamental Investors Fund Class R2) and AHMFX (American High-Income Municipal Bond Fund Class F-2) are both mutual funds - RFNBX is a Large Cap Blend Equities fund actively managed by Capital Group, while AHMFX is a High Yield Muni fund actively managed by Capital Group. Both are actively managed. Over the past 10 years, RFNBX returned 13.85%/yr vs 3.46%/yr for AHMFX. At a correlation of -0.08, they often move in opposite directions. RFNBX charges 1.36%/yr vs 0.42%/yr for AHMFX.

Performance

RFNBX vs. AHMFX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in American Funds Fundamental Investors Fund Class R2 (RFNBX) and American High-Income Municipal Bond Fund Class F-2 (AHMFX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, RFNBX achieves a 14.75% return, which is significantly higher than AHMFX's 2.13% return. Over the past 10 years, RFNBX has outperformed AHMFX with an annualized return of 13.85%, while AHMFX has yielded a comparatively lower 3.46% annualized return.

RFNBX

• 1D: 0.21%
• 1M: 6.02%
• YTD: 14.75%
• 6M: 15.93%
• 1Y: 34.27%
• 3Y*: 25.11%
• 5Y*: 13.90%
• 10Y*: 13.85%

AHMFX

• 1D: 0.00%
• 1M: 0.67%
• YTD: 2.13%
• 6M: 2.70%
• 1Y: 8.36%
• 3Y*: 6.33%
• 5Y*: 1.87%
• 10Y*: 3.46%

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

RFNBX vs. AHMFX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
RFNBX American Funds Fundamental Investors Fund Class R2	14.75%	23.22%	21.80%	24.89%	-17.32%	21.49%	12.51%	26.09%	-8.89%	21.82%
AHMFX American High-Income Municipal Bond Fund Class F-2	2.13%	6.03%	6.45%	7.04%	-12.44%	5.49%	4.61%	9.12%	1.80%	9.09%

Correlation

The correlation between RFNBX and AHMFX is 0.14, which is low. Their price movements are largely independent, making them effective diversification partners.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.14
Correlation (3Y) Calculated over the trailing 3-year period	0.14
Correlation (5Y) Calculated over the trailing 5-year period	0.11
Correlation (10Y) Calculated over the trailing 10-year period	0.03
Correlation (All Time) Calculated using the full available price history since Jan 5, 2009	-0.08

The correlation between RFNBX and AHMFX shifts across timeframes, from -0.08 (all time) to 0.14 (1 year), reflecting how their relationship changes across market environments.

Return for Risk

RFNBX vs. AHMFX — Risk / Return Rank

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

RFNBX

RFNBX Risk / Return Rank: 73
RFNBX Sharpe Ratio Rank: 79
RFNBX Sortino Ratio Rank: 68
RFNBX Omega Ratio Rank: 68
RFNBX Calmar Ratio Rank: 71
RFNBX Martin Ratio Rank: 80

AHMFX

AHMFX Risk / Return Rank: 75
AHMFX Sharpe Ratio Rank: 82
AHMFX Sortino Ratio Rank: 89
AHMFX Omega Ratio Rank: 89
AHMFX Calmar Ratio Rank: 62
AHMFX Martin Ratio Rank: 54

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.

RFNBX vs. AHMFX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for American Funds Fundamental Investors Fund Class R2 (RFNBX) and American High-Income Municipal Bond Fund Class F-2 (AHMFX). 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.

	RFNBX	AHMFX	Difference
Sharpe ratio Return per unit of total volatility	2.57	2.65	-0.08
Sortino ratio Return per unit of downside risk	3.44	4.32	-0.88
Omega ratio Gain probability vs. loss probability	1.46	1.63	-0.17
Calmar ratio Return relative to maximum drawdown	3.27	3.04	+0.23
Martin ratio Return relative to average drawdown	15.10	10.89	+4.20
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

RFNBX vs. AHMFX - Sharpe Ratio Comparison

The current RFNBX Sharpe Ratio is 2.57, which is comparable to the AHMFX Sharpe Ratio of 2.65. The chart below compares the historical Sharpe Ratios of RFNBX and AHMFX, 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

	RFNBX	AHMFX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.57	2.65	-0.08
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.83	0.39	+0.44
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.78	0.76	+0.02
Sharpe Ratio (All Time) Calculated using the full available price history	0.60	1.54	-0.94

Drawdowns

RFNBX vs. AHMFX - Drawdown Comparison

The maximum RFNBX drawdown since its inception was -53.81%, which is greater than AHMFX's maximum drawdown of -17.65%. Use the drawdown chart below to compare losses from any high point for RFNBX and AHMFX.

Drawdown Indicators

	RFNBX	AHMFX	Difference
Max Drawdown Largest peak-to-trough decline	-53.81%	-17.65%	-36.16%
Max Drawdown (1Y) Largest decline over 1 year	-10.78%	-2.76%	-8.02%
Max Drawdown (3Y) Largest decline over 3 years	-18.11%	-6.20%	-11.91%
Max Drawdown (5Y) Largest decline over 5 years	-25.53%	-17.65%	-7.88%
Max Drawdown (10Y) Largest decline over 10 years	-33.96%	-17.65%	-16.31%
Current Drawdown Current decline from peak	0.00%	-0.15%	+0.15%
Average Drawdown Average peak-to-trough decline	-7.24%	-2.37%	-4.87%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.33%	0.77%	+1.56%

Volatility

RFNBX vs. AHMFX - Volatility Comparison

American Funds Fundamental Investors Fund Class R2 (RFNBX) has a higher volatility of 3.68% compared to American High-Income Municipal Bond Fund Class F-2 (AHMFX) at 1.10%. This indicates that RFNBX's price experiences larger fluctuations and is considered to be riskier than AHMFX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	RFNBX	AHMFX	Difference
Volatility (1M) Calculated over the trailing 1-month period	3.68%	1.10%	+2.58%
Volatility (6M) Calculated over the trailing 6-month period	10.83%	2.24%	+8.59%
Volatility (1Y) Calculated over the trailing 1-year period	13.78%	3.06%	+10.72%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	16.80%	4.86%	+11.94%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	17.74%	4.55%	+13.19%

RFNBX vs. AHMFX - Expense Ratio Comparison

RFNBX has a 1.36% expense ratio, which is higher than AHMFX's 0.42% expense ratio.

Dividends

RFNBX vs. AHMFX - Dividend Comparison

RFNBX's dividend yield for the trailing twelve months is around 6.88%, more than AHMFX's 4.13% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
AHMFX American High-Income Municipal Bond Fund Class F-2	4.13%	5.58%	4.04%	2.97%	2.71%	3.44%	3.60%	3.68%	3.88%	4.19%	3.74%	4.19%
RFNBX American Funds Fundamental Investors Fund Class R2	6.88%	7.90%	8.19%	5.13%	4.16%	10.27%	0.83%	6.20%	8.38%	6.54%	3.99%	5.32%

Frequently Asked Questions

Can I hold both RFNBX and AHMFX in my portfolio?

RFNBX and AHMFX have a correlation of 0.14, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, RFNBX or AHMFX?

RFNBX has higher volatility (3.68%) compared to AHMFX (1.10%). In terms of maximum drawdown, RFNBX dropped -53.81% vs AHMFX's -17.65%.

Which has better risk-adjusted returns?

AHMFX currently has the higher Sharpe Ratio (2.65 vs 2.57), 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.