FUNFX vs. RCKSX

Last updated Jun 4, 2026

FUNFX (American Funds Fundamental Investors® Class F-3) and RCKSX (Rock Oak Core Growth Fund) are both Large Cap Blend Equities funds. Over the past 5 years, FUNFX returned 15.27%/yr vs 7.42%/yr for RCKSX. Their correlation of 0.84 suggests significant overlap in exposure. FUNFX charges 0.28%/yr vs 1.25%/yr for RCKSX.

Performance

FUNFX vs. RCKSX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in American Funds Fundamental Investors® Class F-3 (FUNFX) and Rock Oak Core Growth Fund (RCKSX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, FUNFX achieves a 15.28% return, which is significantly higher than RCKSX's 14.10% return.

FUNFX

• 1D: 0.01%
• 1M: 5.92%
• YTD: 15.28%
• 6M: 16.32%
• 1Y: 34.95%
• 3Y*: 26.48%
• 5Y*: 15.27%
• 10Y*: —

RCKSX

• 1D: -0.13%
• 1M: 1.87%
• YTD: 14.10%
• 6M: 14.42%
• 1Y: 20.18%
• 3Y*: 19.62%
• 5Y*: 7.42%
• 10Y*: 10.85%

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

FUNFX vs. RCKSX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
FUNFX American Funds Fundamental Investors® Class F-3	15.28%	24.57%	23.13%	26.25%	-16.38%	22.81%	15.28%	27.47%	-7.87%	19.59%
RCKSX Rock Oak Core Growth Fund	14.10%	12.99%	15.12%	15.57%	-18.09%	9.96%	13.75%	19.05%	-2.14%	17.38%

Correlation

The correlation between FUNFX and RCKSX is 0.60, 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	0.60
Correlation (3Y) Calculated over the trailing 3-year period	0.71
Correlation (5Y) Calculated over the trailing 5-year period	0.81
Correlation (All Time) Calculated using the full available price history since Feb 2, 2017	0.84

Over the past year, the correlation between FUNFX and RCKSX has dropped to 0.60 - well below their long-term average of 0.84, suggesting their price drivers have been diverging.

Return for Risk

FUNFX vs. RCKSX — Risk / Return Rank

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

FUNFX

FUNFX Risk / Return Rank: 76
FUNFX Sharpe Ratio Rank: 81
FUNFX Sortino Ratio Rank: 71
FUNFX Omega Ratio Rank: 71
FUNFX Calmar Ratio Rank: 74
FUNFX Martin Ratio Rank: 83

RCKSX

RCKSX Risk / Return Rank: 56
RCKSX Sharpe Ratio Rank: 39
RCKSX Sortino Ratio Rank: 40
RCKSX Omega Ratio Rank: 34
RCKSX Calmar Ratio Rank: 93
RCKSX Martin Ratio Rank: 75

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.

FUNFX vs. RCKSX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for American Funds Fundamental Investors® Class F-3 (FUNFX) and Rock Oak Core Growth Fund (RCKSX). 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.

	FUNFX	RCKSX	Difference
Sharpe ratio: Return per unit of total volatility	2.61	1.83	+0.78
Sortino ratio: Return per unit of downside risk	3.50	2.66	+0.85
Omega ratio: Gain probability vs. loss probability	1.47	1.31	+0.17
Calmar ratio: Return relative to maximum drawdown	3.38	5.11	-1.73
Martin ratio: Return relative to average drawdown	15.68	14.18	+1.50
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

FUNFX vs. RCKSX - Sharpe Ratio Comparison

The current FUNFX Sharpe Ratio is 2.61, which is higher than the RCKSX Sharpe Ratio of 1.83. The chart below compares the historical Sharpe Ratios of FUNFX and RCKSX, 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

	FUNFX	RCKSX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.61	1.83	+0.78
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.91	0.48	+0.44
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	—	0.62	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.84	0.38	+0.46

Drawdowns

FUNFX vs. RCKSX - Drawdown Comparison

The maximum FUNFX drawdown since its inception was -33.92%, smaller than the maximum RCKSX drawdown of -57.88%. Use the drawdown chart below to compare losses from any high point for FUNFX and RCKSX.

Drawdown Indicators

	FUNFX	RCKSX	Difference
Max Drawdown Largest peak-to-trough decline	-33.92%	-57.88%	+23.96%
Max Drawdown (1Y) Largest decline over 1 year	-10.62%	-4.14%	-6.48%
Max Drawdown (3Y) Largest decline over 3 years	-17.93%	-18.22%	+0.29%
Max Drawdown (5Y) Largest decline over 5 years	-24.88%	-22.54%	-2.34%
Max Drawdown (10Y) Largest decline over 10 years	—	-33.10%	—
Current Drawdown Current decline from peak	0.00%	-0.60%	+0.60%
Average Drawdown Average peak-to-trough decline	-4.71%	-9.51%	+4.80%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.29%	1.49%	+0.80%

Volatility

FUNFX vs. RCKSX - Volatility Comparison

American Funds Fundamental Investors® Class F-3 (FUNFX) has a higher volatility of 3.68% compared to Rock Oak Core Growth Fund (RCKSX) at 2.94%. This indicates that FUNFX's price experiences larger fluctuations and is considered to be riskier than RCKSX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	FUNFX	RCKSX	Difference
Volatility (1M) Calculated over the trailing 1-month period	3.68%	2.94%	+0.74%
Volatility (6M) Calculated over the trailing 6-month period	10.82%	8.06%	+2.76%
Volatility (1Y) Calculated over the trailing 1-year period	13.75%	11.56%	+2.19%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	16.80%	15.66%	+1.14%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	18.11%	17.55%	+0.56%

FUNFX vs. RCKSX - Expense Ratio Comparison

FUNFX has a 0.28% expense ratio, which is lower than RCKSX's 1.25% expense ratio.

Dividends

FUNFX vs. RCKSX - Dividend Comparison

FUNFX's dividend yield for the trailing twelve months is around 7.69%, more than RCKSX's 5.48% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FUNFX American Funds Fundamental Investors® Class F-3	7.69%	8.83%	9.21%	6.10%	5.33%	11.29%	2.90%	7.21%	9.65%	7.57%	0.00%	0.00%
RCKSX Rock Oak Core Growth Fund	5.48%	6.26%	0.47%	0.71%	1.00%	4.31%	16.56%	3.18%	0.59%	5.91%	0.70%	3.21%

Frequently Asked Questions

Can I hold both FUNFX and RCKSX in my portfolio?

FUNFX and RCKSX have a correlation of 0.60, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, FUNFX or RCKSX?

FUNFX has higher volatility (3.68%) compared to RCKSX (2.94%). In terms of maximum drawdown, FUNFX dropped -33.92% vs RCKSX's -57.88%.

Which has better risk-adjusted returns?

FUNFX currently has the higher Sharpe Ratio (2.61 vs 1.83), 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.