FMDGX vs. MEFAX

Last updated Jun 24, 2026

FMDGX (Fidelity Mid Cap Growth Index Fund) and MEFAX (MassMutual Mid Cap Growth Fund) are both Mid Cap Growth Equities funds. Over the past 5 years, FMDGX returned 5.63%/yr vs 2.43%/yr for MEFAX. With a 0.95 correlation, they move nearly in lockstep. FMDGX charges 0.05%/yr vs 1.20%/yr for MEFAX.

Performance

FMDGX vs. MEFAX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Fidelity Mid Cap Growth Index Fund (FMDGX) and MassMutual Mid Cap Growth Fund (MEFAX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, FMDGX achieves a 3.82% return, which is significantly lower than MEFAX's 4.72% return.

FMDGX

• 1D: -0.11%
• 1M: 1.82%
• YTD: 3.82%
• 6M: 1.82%
• 1Y: 5.26%
• 3Y*: 15.69%
• 5Y*: 5.63%
• 10Y*: —

MEFAX

• 1D: 0.00%
• 1M: 1.46%
• YTD: 4.72%
• 6M: 3.27%
• 1Y: 9.16%
• 3Y*: 9.36%
• 5Y*: 2.43%
• 10Y*: 10.68%

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

FMDGX vs. MEFAX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019
FMDGX Fidelity Mid Cap Growth Index Fund	3.82%	8.60%	22.03%	25.79%	-26.67%	12.67%	34.84%	4.63%
MEFAX MassMutual Mid Cap Growth Fund	4.72%	3.19%	10.80%	19.11%	-24.58%	13.75%	25.52%	11.93%

Correlation

The correlation between FMDGX and MEFAX 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	0.93
Correlation (5Y) Calculated over the trailing 5-year period	0.95
Correlation (All Time) Calculated using the full available price history since Jul 17, 2019	0.95

The correlation between FMDGX and MEFAX has been stable across timeframes, ranging from 0.92 to 0.95 - a consistent structural relationship.

Return for Risk

FMDGX vs. MEFAX — Risk / Return Rank

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

FMDGX

FMDGX Risk / Return Rank: 5
FMDGX Sharpe Ratio Rank: 5
FMDGX Sortino Ratio Rank: 5
FMDGX Omega Ratio Rank: 5
FMDGX Calmar Ratio Rank: 5
FMDGX Martin Ratio Rank: 6

MEFAX

MEFAX Risk / Return Rank: 10
MEFAX Sharpe Ratio Rank: 9
MEFAX Sortino Ratio Rank: 9
MEFAX Omega Ratio Rank: 8
MEFAX Calmar Ratio Rank: 11
MEFAX Martin Ratio Rank: 13

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.

FMDGX vs. MEFAX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity Mid Cap Growth Index Fund (FMDGX) and MassMutual Mid Cap Growth Fund (MEFAX). 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.

	FMDGX	MEFAX	Difference
Sharpe ratio: Return per unit of total volatility	0.36	0.67	-0.31
Sortino ratio: Return per unit of downside risk	0.62	1.05	-0.43
Omega ratio: Gain probability vs. loss probability	1.07	1.12	-0.05
Calmar ratio: Return relative to maximum drawdown	0.42	0.96	-0.55
Martin ratio: Return relative to average drawdown	1.20	3.50	-2.30

FMDGX vs. MEFAX - Sharpe Ratio Comparison

The current FMDGX Sharpe Ratio is 0.36, which is lower than the MEFAX Sharpe Ratio of 0.67. The chart below compares the historical Sharpe Ratios of FMDGX and MEFAX, 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

FMDGX vs. MEFAX - Drawdown Comparison

The maximum FMDGX drawdown since its inception was -38.59%, smaller than the maximum MEFAX drawdown of -56.04%. Use the drawdown chart below to compare losses from any high point for FMDGX and MEFAX.

Drawdown Indicators

	FMDGX	MEFAX	Difference
Max Drawdown Largest peak-to-trough decline	-38.59%	-56.04%	+17.45%
Max Drawdown (1Y) Largest decline over 1 year	-14.75%	-10.45%	-4.30%
Max Drawdown (3Y) Largest decline over 3 years	-25.30%	-34.46%	+9.16%
Max Drawdown (5Y) Largest decline over 5 years	-38.59%	-45.14%	+6.55%
Max Drawdown (10Y) Largest decline over 10 years	—	-45.14%	—
Current Drawdown Current decline from peak	-2.08%	-14.69%	+12.61%
Average Drawdown Average peak-to-trough decline	-11.14%	-11.43%	+0.29%
Ulcer Index Depth and duration of drawdowns from previous peaks	5.09%	2.87%	+2.22%

Volatility

FMDGX vs. MEFAX - Volatility Comparison

Fidelity Mid Cap Growth Index Fund (FMDGX) has a higher volatility of 5.70% compared to MassMutual Mid Cap Growth Fund (MEFAX) at 5.22%. This indicates that FMDGX's price experiences larger fluctuations and is considered to be riskier than MEFAX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	FMDGX	MEFAX	Difference
Volatility (1M) Calculated over the trailing 1-month period	5.70%	5.22%	+0.48%
Volatility (6M) Calculated over the trailing 6-month period	13.38%	11.96%	+1.42%
Volatility (1Y) Calculated over the trailing 1-year period	17.07%	15.15%	+1.92%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	22.45%	27.52%	-5.07%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	24.30%	23.97%	+0.33%

FMDGX vs. MEFAX - Expense Ratio Comparison

FMDGX has a 0.05% expense ratio, which is lower than MEFAX's 1.20% expense ratio.

Dividends

FMDGX vs. MEFAX - Dividend Comparison

FMDGX's dividend yield for the trailing twelve months is around 1.79%, less than MEFAX's 32.62% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FMDGX Fidelity Mid Cap Growth Index Fund	1.79%	1.85%	0.47%	0.63%	0.81%	6.43%	0.36%	0.29%	0.00%	0.00%	0.00%	0.00%
MEFAX MassMutual Mid Cap Growth Fund	32.62%	34.16%	21.40%	7.62%	20.71%	29.49%	6.92%	12.81%	12.06%	7.66%	5.32%	10.27%

Frequently Asked Questions

Can I hold both FMDGX and MEFAX in my portfolio?

With a correlation of 0.92, FMDGX and MEFAX 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, FMDGX or MEFAX?

FMDGX has higher volatility (5.70%) compared to MEFAX (5.22%). In terms of maximum drawdown, FMDGX dropped -38.59% vs MEFAX's -56.04%.

Which has better risk-adjusted returns?

MEFAX currently has the higher Sharpe Ratio (0.67 vs 0.36), 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.