RFNGX vs. FUMIX

Last updated Jun 19, 2026

RFNGX (American Funds Fundamental Investors Fund Class R6) and FUMIX (Fidelity SAI U.S. Momentum Index Fund) are both Large Cap Growth Equities funds. Over the past 5 years, RFNGX returned 15.03%/yr vs 17.68%/yr for FUMIX. Their correlation of 0.87 suggests significant overlap in exposure. RFNGX charges 0.28%/yr vs 0.11%/yr for FUMIX.

Performance

RFNGX vs. FUMIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in American Funds Fundamental Investors Fund Class R6 (RFNGX) and Fidelity SAI U.S. Momentum Index Fund (FUMIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, RFNGX achieves a 13.30% return, which is significantly lower than FUMIX's 30.85% return.

RFNGX

• 1D: -0.98%
• 1M: 2.53%
• YTD: 13.30%
• 6M: 15.84%
• 1Y: 31.27%
• 3Y*: 24.50%
• 5Y*: 15.03%
• 10Y*: 15.14%

FUMIX

• 1D: 1.84%
• 1M: 9.79%
• YTD: 30.85%
• 6M: 30.64%
• 1Y: 40.57%
• 3Y*: 32.61%
• 5Y*: 17.68%
• 10Y*: —

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

RFNGX vs. FUMIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
RFNGX American Funds Fundamental Investors Fund Class R6	13.30%	24.58%	22.77%	26.25%	-16.38%	22.83%	13.72%	27.48%	-7.09%	19.15%
FUMIX Fidelity SAI U.S. Momentum Index Fund	30.85%	17.01%	33.39%	14.67%	-15.79%	22.56%	29.92%	24.16%	-1.41%	22.71%

Correlation

The correlation between RFNGX and FUMIX is 0.86, 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	0.86
Correlation (3Y) Calculated over the trailing 3-year period	0.89
Correlation (5Y) Calculated over the trailing 5-year period	0.89
Correlation (All Time) Calculated using the full available price history since Feb 9, 2017	0.87

The correlation between RFNGX and FUMIX has been stable across timeframes, ranging from 0.86 to 0.89 - a consistent structural relationship.

Return for Risk

RFNGX vs. FUMIX — Risk / Return Rank

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

RFNGX

RFNGX Risk / Return Rank: 68
RFNGX Sharpe Ratio Rank: 68
RFNGX Sortino Ratio Rank: 61
RFNGX Omega Ratio Rank: 62
RFNGX Calmar Ratio Rank: 68
RFNGX Martin Ratio Rank: 79

FUMIX

FUMIX Risk / Return Rank: 77
FUMIX Sharpe Ratio Rank: 73
FUMIX Sortino Ratio Rank: 68
FUMIX Omega Ratio Rank: 67
FUMIX Calmar Ratio Rank: 85
FUMIX Martin Ratio Rank: 91

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.

RFNGX vs. FUMIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for American Funds Fundamental Investors Fund Class R6 (RFNGX) and Fidelity SAI U.S. Momentum Index Fund (FUMIX). 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.

Values are calculated on a 1-year rolling basis and updated daily. Risk-adjusted metrics are more stable over longer periods — use the period switch above to explore them.

	RFNGX	FUMIX	Difference
Sharpe ratio: Return per unit of total volatility	2.16	2.22	-0.07
Sortino ratio: Return per unit of downside risk	2.91	3.02	-0.11
Omega ratio: Gain probability vs. loss probability	1.39	1.40	-0.01
Calmar ratio: Return relative to maximum drawdown	2.95	3.73	-0.78
Martin ratio: Return relative to average drawdown	13.31	16.72	-3.41

RFNGX vs. FUMIX - Sharpe Ratio Comparison

The current RFNGX Sharpe Ratio is 2.16, which is comparable to the FUMIX Sharpe Ratio of 2.22. The chart below compares the historical Sharpe Ratios of RFNGX and FUMIX, calculated using daily returns over the previous 12 months. A higher Sharpe Ratio indicates better risk-adjusted performance relative to the risk-free rate.

Drawdowns

RFNGX vs. FUMIX - Drawdown Comparison

The maximum RFNGX drawdown since its inception was -33.90%, roughly equal to the maximum FUMIX drawdown of -33.36%. Use the drawdown chart below to compare losses from any high point for RFNGX and FUMIX.

Drawdown Indicators

	RFNGX	FUMIX	Difference
Max Drawdown Largest peak-to-trough decline	-33.90%	-33.36%	-0.54%
Max Drawdown (1Y) Largest decline over 1 year	-10.62%	-10.99%	+0.37%
Max Drawdown (3Y) Largest decline over 3 years	-17.92%	-19.90%	+1.98%
Max Drawdown (5Y) Largest decline over 5 years	-24.88%	-27.66%	+2.78%
Max Drawdown (10Y) Largest decline over 10 years	-33.90%	—	—
Current Drawdown Current decline from peak	-1.71%	0.00%	-1.71%
Average Drawdown Average peak-to-trough decline	-4.01%	-6.29%	+2.28%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.35%	2.44%	-0.09%

Volatility

RFNGX vs. FUMIX - Volatility Comparison

The current volatility for American Funds Fundamental Investors Fund Class R6 (RFNGX) is 5.58%, while Fidelity SAI U.S. Momentum Index Fund (FUMIX) has a volatility of 7.72%. This indicates that RFNGX experiences smaller price fluctuations and is considered to be less risky than FUMIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	RFNGX	FUMIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	5.58%	7.72%	-2.14%
Volatility (6M) Calculated over the trailing 6-month period	11.71%	16.07%	-4.36%
Volatility (1Y) Calculated over the trailing 1-year period	14.56%	18.43%	-3.87%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	16.95%	21.38%	-4.43%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	17.79%	21.83%	-4.04%

RFNGX vs. FUMIX - Expense Ratio Comparison

RFNGX has a 0.28% expense ratio, which is higher than FUMIX's 0.11% expense ratio.

Dividends

RFNGX vs. FUMIX - Dividend Comparison

RFNGX's dividend yield for the trailing twelve months is around 7.64%, more than FUMIX's 2.12% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FUMIX Fidelity SAI U.S. Momentum Index Fund	2.12%	2.77%	5.89%	18.09%	2.10%	20.67%	8.68%	2.09%	3.84%	0.88%	0.00%	0.00%
RFNGX American Funds Fundamental Investors Fund Class R6	7.64%	8.82%	8.91%	6.10%	5.33%	11.29%	1.77%	7.21%	10.67%	7.56%	5.01%	6.01%

Frequently Asked Questions

Can I hold both RFNGX and FUMIX in my portfolio?

RFNGX and FUMIX have a correlation of 0.86, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, RFNGX or FUMIX?

FUMIX has higher volatility (7.72%) compared to RFNGX (5.58%). In terms of maximum drawdown, RFNGX dropped -33.90% vs FUMIX's -33.36%.

Which has better risk-adjusted returns?

FUMIX currently has the higher Sharpe Ratio (2.22 vs 2.16), 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.