AMPCX vs. MRFOX

Last updated Aug 1, 2026

AMPCX (American Funds AMCAP Fund Class C) and MRFOX (Marshfield Concentrated Opportunity Fund) are both Large Cap Growth Equities funds. Over the past 10 years, AMPCX returned 11.22%/yr vs 15.92%/yr for MRFOX. Their 0.72 correlation means they have sometimes moved together and sometimes differently. AMPCX charges 1.40%/yr vs 1.05%/yr for MRFOX.

Performance

AMPCX vs. MRFOX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in American Funds AMCAP Fund Class C (AMPCX) and Marshfield Concentrated Opportunity Fund (MRFOX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, AMPCX achieves a 2.41% return, which is significantly lower than MRFOX's 4.87% return. Over the past 10 years, AMPCX has underperformed MRFOX with an annualized return of 11.22%, while MRFOX has yielded a comparatively higher 15.92% annualized return.

AMPCX

• 1D: 1.02%
• 1M: -2.90%
• 6M: 2.21%
• YTD: 2.41%
• 1Y: 10.31%
• 3Y*: 15.01%
• 5Y*: 7.20%
• 10Y*: 11.22%
• ALL TIME*: 7.79%

MRFOX

• 1D: -1.24%
• 1M: -0.50%
• 6M: 3.84%
• YTD: 4.87%
• 1Y: 11.84%
• 3Y*: 13.29%
• 5Y*: 11.49%
• 10Y*: 15.92%
• ALL TIME*: 15.58%

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

Liquidity Comparison

Position	Avg. Volume Value (2W)	Avg. Volume Value (1M)	Avg. Volume Value (3M)
AMPCX American Funds AMCAP Fund Class C	$0.00	$0.00	$0.00
MRFOX Marshfield Concentrated Opportunity Fund	$0.00	$0.00	$0.00

AMPCX vs. MRFOX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
AMPCX American Funds AMCAP Fund Class C	2.41%	16.78%	20.17%	30.08%	-29.17%	22.77%	20.52%	25.37%	-5.50%	21.11%
MRFOX Marshfield Concentrated Opportunity Fund	4.87%	10.05%	17.10%	17.68%	5.06%	17.71%	15.19%	36.26%	1.89%	25.92%

Correlation

The correlation between AMPCX and MRFOX is 0.28, which is low. Their historical price movements had little consistent relationship.

	Correlation
Correlation (1Y) Focuses on recent behavior, but can change the most.	0.28
Correlation (3Y) Balances recent behavior with more history.	0.51
Correlation (5Y) Shows whether the relationship held over a longer period.	0.64
Correlation (10Y) Provides a long-term view across more market conditions.	0.71
Correlation (All Time) Calculated using the full available price history since Jan 4, 2016	0.72

Over the past year, the correlation between AMPCX and MRFOX has dropped to 0.28 - well below their long-term average of 0.72, suggesting their price drivers have been diverging.

Return for Risk

AMPCX vs. MRFOX — Risk / Return Rank

Compare historical risk-adjusted metric ranks over the past 12 months.

AMPCX

AMPCX Risk / Return Rank: 14
AMPCX Sharpe Ratio Rank: 14
AMPCX Sortino Ratio Rank: 14
AMPCX Omega Ratio Rank: 14
AMPCX Calmar Ratio Rank: 12
AMPCX Martin Ratio Rank: 16

MRFOX

MRFOX Risk / Return Rank: 35
MRFOX Sharpe Ratio Rank: 34
MRFOX Sortino Ratio Rank: 37
MRFOX Omega Ratio Rank: 32
MRFOX Calmar Ratio Rank: 38
MRFOX Martin Ratio Rank: 32

The rank (0–100) uses a weighted average of the Sharpe, Sortino, Omega, Calmar, and Martin percentile ranks for the trailing 12 months. Higher means stronger historical risk-adjusted performance within the peer group.

AMPCX vs. MRFOX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for American Funds AMCAP Fund Class C (AMPCX) and Marshfield Concentrated Opportunity Fund (MRFOX). 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.

	AMPCX	MRFOX	Difference
Sharpe ratio: Return per unit of total volatility	0.52	1.05	-0.53
Sortino ratio: Return per unit of downside risk	0.82	1.62	-0.80
Omega ratio: Gain probability vs. loss probability	1.10	1.19	-0.08
Calmar ratio: Return relative to maximum drawdown	0.57	1.55	-0.98
Martin ratio: Return relative to average drawdown	2.19	4.55	-2.36

AMPCX vs. MRFOX - Sharpe Ratio Comparison

The current AMPCX Sharpe Ratio is 0.52, which is lower than the MRFOX Sharpe Ratio of 1.05. The chart below compares the historical Sharpe Ratios of AMPCX and MRFOX, 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

AMPCX vs. MRFOX - Drawdown Comparison

The maximum AMPCX drawdown since its inception was -53.38%, which is greater than MRFOX's maximum drawdown of -29.10%. Use the drawdown chart below to compare losses from any high point for AMPCX and MRFOX.

Drawdown Indicators

	AMPCX	MRFOX	Difference
Max Drawdown Largest peak-to-trough decline	-53.38%	-29.10%	-24.28%
Max Drawdown (1Y) Largest decline over 1 year	-14.33%	-7.03%	-7.30%
Max Drawdown (3Y) Largest decline over 3 years	-19.81%	-7.91%	-11.90%
Max Drawdown (5Y) Largest decline over 5 years	-35.67%	-12.98%	-22.69%
Max Drawdown (10Y) Largest decline over 10 years	-35.67%	-29.10%	-6.57%
Current Drawdown Current decline from peak	-4.14%	-1.37%	-2.77%
Average Drawdown Average peak-to-trough decline	-9.18%	-2.34%	-6.84%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.73%	2.38%	+1.35%

Volatility

AMPCX vs. MRFOX - Volatility Comparison

The current volatility for American Funds AMCAP Fund Class C (AMPCX) is 3.78%, while Marshfield Concentrated Opportunity Fund (MRFOX) has a volatility of 4.45%. This indicates that AMPCX experiences smaller price fluctuations and is considered to be less risky than MRFOX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	AMPCX	MRFOX	Difference
Volatility (1M) Calculated over the trailing 1-month period	3.78%	4.45%	-0.67%
Volatility (6M) Calculated over the trailing 6-month period	12.55%	7.80%	+4.75%
Volatility (1Y) Calculated over the trailing 1-year period	15.73%	10.40%	+5.33%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	19.43%	12.17%	+7.26%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	18.76%	14.18%	+4.58%

AMPCX vs. MRFOX - Expense Ratio Comparison

AMPCX has a 1.40% expense ratio, which is higher than MRFOX's 1.05% expense ratio.

Dividends

AMPCX vs. MRFOX - Dividend Comparison

AMPCX's dividend yield for the trailing twelve months is around 17.33%, more than MRFOX's 1.54% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
AMPCX American Funds AMCAP Fund Class C	17.33%	11.35%	9.83%	3.32%	9.21%	7.09%	4.32%	5.06%	8.25%	5.61%	3.77%	9.83%
MRFOX Marshfield Concentrated Opportunity Fund	1.54%	1.62%	4.59%	0.46%	0.35%	6.78%	2.68%	1.39%	1.94%	2.06%	0.60%	0.00%

Frequently Asked Questions

Can I hold both AMPCX and MRFOX in my portfolio?

AMPCX and MRFOX have a correlation of 0.28, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, AMPCX or MRFOX?

MRFOX has higher volatility (4.45%) compared to AMPCX (3.78%). In terms of maximum drawdown, AMPCX dropped -53.38% vs MRFOX's -29.10%.

Which has better risk-adjusted returns?

MRFOX currently has the higher Sharpe Ratio (1.05 vs 0.52), 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.