GAFFX vs. MFEIX

Last updated Jun 4, 2026

GAFFX (American Funds Growth Fund of Amer F3) and MFEIX (MFS Growth I) are both Large Cap Growth Equities funds. Over the past 5 years, GAFFX returned 12.86%/yr vs 14.38%/yr for MFEIX. Their correlation of 0.94 suggests significant overlap in exposure. GAFFX charges 0.30%/yr vs 0.60%/yr for MFEIX.

Performance

GAFFX vs. MFEIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in American Funds Growth Fund of Amer F3 (GAFFX) and MFS Growth I (MFEIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, GAFFX achieves a 10.23% return, which is significantly higher than MFEIX's 6.29% return.

GAFFX

• 1D: -0.33%
• 1M: 6.84%
• YTD: 10.23%
• 6M: 9.86%
• 1Y: 26.59%
• 3Y*: 25.53%
• 5Y*: 12.86%
• 10Y*: —

MFEIX

• 1D: -0.34%
• 1M: 4.75%
• YTD: 6.29%
• 6M: 5.95%
• 1Y: 17.64%
• 3Y*: 26.61%
• 5Y*: 14.38%
• 10Y*: 17.67%

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

GAFFX vs. MFEIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
GAFFX American Funds Growth Fund of Amer F3	10.23%	20.09%	28.41%	37.68%	-30.54%	19.67%	38.31%	28.57%	-2.89%	20.76%
MFEIX MFS Growth I	6.29%	12.34%	49.67%	36.15%	-31.14%	23.59%	31.65%	37.69%	2.30%	25.55%

Correlation

The correlation between GAFFX and MFEIX 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	0.92
Correlation (5Y) Calculated over the trailing 5-year period	0.94
Correlation (All Time) Calculated using the full available price history since Feb 2, 2017	0.94

The correlation between GAFFX and MFEIX has been stable across timeframes, ranging from 0.92 to 0.94 - a consistent structural relationship.

Return for Risk

GAFFX vs. MFEIX — Risk / Return Rank

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

GAFFX

GAFFX Risk / Return Rank: 35
GAFFX Sharpe Ratio Rank: 39
GAFFX Sortino Ratio Rank: 35
GAFFX Omega Ratio Rank: 37
GAFFX Calmar Ratio Rank: 28
GAFFX Martin Ratio Rank: 35

MFEIX

MFEIX Risk / Return Rank: 14
MFEIX Sharpe Ratio Rank: 17
MFEIX Sortino Ratio Rank: 15
MFEIX Omega Ratio Rank: 16
MFEIX Calmar Ratio Rank: 11
MFEIX Martin Ratio Rank: 11

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.

GAFFX vs. MFEIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for American Funds Growth Fund of Amer F3 (GAFFX) and MFS Growth I (MFEIX). 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.

	GAFFX	MFEIX	Difference
Sharpe ratio: Return per unit of total volatility	1.80	1.15	+0.65
Sortino ratio: Return per unit of downside risk	2.46	1.64	+0.83
Omega ratio: Gain probability vs. loss probability	1.32	1.21	+0.12
Calmar ratio: Return relative to maximum drawdown	1.99	1.05	+0.93
Martin ratio: Return relative to average drawdown	7.76	3.43	+4.34
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

GAFFX vs. MFEIX - Sharpe Ratio Comparison

The current GAFFX Sharpe Ratio is 1.80, which is higher than the MFEIX Sharpe Ratio of 1.15. The chart below compares the historical Sharpe Ratios of GAFFX and MFEIX, 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

	GAFFX	MFEIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.80	1.15	+0.65
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.64	0.66	-0.02
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	—	0.83	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.81	0.44	+0.36

Drawdowns

GAFFX vs. MFEIX - Drawdown Comparison

The maximum GAFFX drawdown since its inception was -36.19%, smaller than the maximum MFEIX drawdown of -72.24%. Use the drawdown chart below to compare losses from any high point for GAFFX and MFEIX.

Drawdown Indicators

	GAFFX	MFEIX	Difference
Max Drawdown Largest peak-to-trough decline	-36.19%	-72.24%	+36.05%
Max Drawdown (1Y) Largest decline over 1 year	-13.71%	-17.30%	+3.59%
Max Drawdown (3Y) Largest decline over 3 years	-21.55%	-23.24%	+1.69%
Max Drawdown (5Y) Largest decline over 5 years	-36.19%	-36.11%	-0.08%
Max Drawdown (10Y) Largest decline over 10 years	—	-36.11%	—
Current Drawdown Current decline from peak	-0.33%	-0.34%	+0.01%
Average Drawdown Average peak-to-trough decline	-7.41%	-23.73%	+16.32%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.50%	5.31%	-1.81%

Volatility

GAFFX vs. MFEIX - Volatility Comparison

American Funds Growth Fund of Amer F3 (GAFFX) and MFS Growth I (MFEIX) have volatilities of 3.67% and 3.59%, respectively, indicating that both stocks experience similar levels of price fluctuations. This suggests that the risk associated with both stocks, as measured by volatility, is nearly the same. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	GAFFX	MFEIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	3.67%	3.59%	+0.08%
Volatility (6M) Calculated over the trailing 6-month period	11.65%	12.24%	-0.59%
Volatility (1Y) Calculated over the trailing 1-year period	15.16%	15.83%	-0.67%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	20.25%	21.90%	-1.65%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	20.14%	21.24%	-1.10%

GAFFX vs. MFEIX - Expense Ratio Comparison

GAFFX has a 0.30% expense ratio, which is lower than MFEIX's 0.60% expense ratio.

Dividends

GAFFX vs. MFEIX - Dividend Comparison

GAFFX's dividend yield for the trailing twelve months is around 9.98%, less than MFEIX's 14.11% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
GAFFX American Funds Growth Fund of Amer F3	9.98%	11.00%	9.30%	7.71%	4.45%	8.50%	4.58%	7.47%	12.37%	7.36%	0.00%	0.00%
MFEIX MFS Growth I	14.11%	14.99%	25.47%	4.86%	1.05%	2.76%	3.57%	1.57%	3.78%	2.50%	1.61%	3.65%

Frequently Asked Questions

Can I hold both GAFFX and MFEIX in my portfolio?

With a correlation of 0.92, GAFFX and MFEIX 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, GAFFX or MFEIX?

GAFFX has higher volatility (3.67%) compared to MFEIX (3.59%). In terms of maximum drawdown, GAFFX dropped -36.19% vs MFEIX's -72.24%.

Which has better risk-adjusted returns?

GAFFX currently has the higher Sharpe Ratio (1.80 vs 1.15), 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.