FMDGX vs. FXAIX

Last updated Aug 1, 2026

FMDGX (Fidelity Mid Cap Growth Index Fund) and FXAIX (Fidelity 500 Index Fund) are both mutual funds - FMDGX is a Mid Cap Growth Equities fund tracking the Russell Midcap Growth Index, while FXAIX is a S&P 500 fund tracking the S&P 500 Index. Both are passively managed. Over the past 5 years, FMDGX returned 4.43%/yr vs 12.68%/yr for FXAIX. Their correlation of 0.87 means they have usually moved in the same direction. FMDGX charges 0.05%/yr vs 0.02%/yr for FXAIX.

Performance

FMDGX vs. FXAIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Fidelity Mid Cap Growth Index Fund (FMDGX) and Fidelity 500 Index Fund (FXAIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, FMDGX achieves a 0.60% return, which is significantly lower than FXAIX's 9.35% return.

FMDGX

• 1D: 2.29%
• 1M: -3.87%
• 6M: 1.50%
• YTD: 0.60%
• 1Y: -0.77%
• 3Y*: 11.99%
• 5Y*: 4.43%
• 10Y*: —
• ALL TIME*: 10.00%

FXAIX

• 1D: 1.66%
• 1M: -0.56%
• 6M: 7.79%
• YTD: 9.35%
• 1Y: 20.63%
• 3Y*: 19.03%
• 5Y*: 12.68%
• 10Y*: 15.00%
• ALL TIME*: 13.89%

*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)
FMDGX Fidelity Mid Cap Growth Index Fund	$0.00	$0.00	$0.00
FXAIX Fidelity 500 Index Fund	$0.00	$0.00	$0.00

FMDGX vs. FXAIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019
FMDGX Fidelity Mid Cap Growth Index Fund	0.60%	8.60%	22.03%	25.79%	-26.67%	12.67%	34.84%	4.63%
FXAIX Fidelity 500 Index Fund	9.35%	17.84%	25.01%	26.29%	-18.14%	28.71%	18.42%	8.53%

Correlation

The correlation between FMDGX and FXAIX is 0.81, meaning they have usually moved in the same direction, including during past declines.

	Correlation
Correlation (1Y) Focuses on recent behavior, but can change the most.	0.81
Correlation (3Y) Balances recent behavior with more history.	0.85
Correlation (5Y) Shows whether the relationship held over a longer period.	0.88
Correlation (All Time) Calculated using the full available price history since Jul 17, 2019	0.87

The correlation between FMDGX and FXAIX has been stable across timeframes, ranging from 0.81 to 0.88 - a consistent structural relationship.

Return for Risk

FMDGX vs. FXAIX — Risk / Return Rank

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

FMDGX

FMDGX Risk / Return Rank: 3
FMDGX Sharpe Ratio Rank: 3
FMDGX Sortino Ratio Rank: 3
FMDGX Omega Ratio Rank: 3
FMDGX Calmar Ratio Rank: 3
FMDGX Martin Ratio Rank: 3

FXAIX

FXAIX Risk / Return Rank: 64
FXAIX Sharpe Ratio Rank: 61
FXAIX Sortino Ratio Rank: 58
FXAIX Omega Ratio Rank: 59
FXAIX Calmar Ratio Rank: 65
FXAIX Martin Ratio Rank: 76

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.

FMDGX vs. FXAIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity Mid Cap Growth Index Fund (FMDGX) and Fidelity 500 Index Fund (FXAIX). 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	FXAIX	Difference
Sharpe ratio: Return per unit of total volatility	-0.17	1.43	-1.60
Sortino ratio: Return per unit of downside risk	-0.12	2.00	-2.12
Omega ratio: Gain probability vs. loss probability	0.99	1.26	-0.27
Calmar ratio: Return relative to maximum drawdown	-0.21	2.06	-2.27
Martin ratio: Return relative to average drawdown	-0.57	8.86	-9.44

FMDGX vs. FXAIX - Sharpe Ratio Comparison

The current FMDGX Sharpe Ratio is -0.17, which is lower than the FXAIX Sharpe Ratio of 1.43. The chart below compares the historical Sharpe Ratios of FMDGX and FXAIX, 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. FXAIX - Drawdown Comparison

The maximum FMDGX drawdown since its inception was -38.59%, which is greater than FXAIX's maximum drawdown of -33.79%. Use the drawdown chart below to compare losses from any high point for FMDGX and FXAIX.

Drawdown Indicators

	FMDGX	FXAIX	Difference
Max Drawdown Largest peak-to-trough decline	-38.59%	-33.79%	-4.80%
Max Drawdown (1Y) Largest decline over 1 year	-14.75%	-8.89%	-5.86%
Max Drawdown (3Y) Largest decline over 3 years	-25.30%	-18.76%	-6.54%
Max Drawdown (5Y) Largest decline over 5 years	-38.59%	-24.50%	-14.09%
Max Drawdown (10Y) Largest decline over 10 years	—	-33.79%	—
Current Drawdown Current decline from peak	-6.20%	-2.11%	-4.09%
Average Drawdown Average peak-to-trough decline	-11.03%	-3.77%	-7.26%
Ulcer Index Depth and duration of drawdowns from previous peaks	5.29%	2.07%	+3.22%

Volatility

FMDGX vs. FXAIX - Volatility Comparison

Fidelity Mid Cap Growth Index Fund (FMDGX) has a higher volatility of 5.15% compared to Fidelity 500 Index Fund (FXAIX) at 3.44%. This indicates that FMDGX's price experiences larger fluctuations and is considered to be riskier than FXAIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	FMDGX	FXAIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	5.15%	3.44%	+1.71%
Volatility (6M) Calculated over the trailing 6-month period	14.00%	10.09%	+3.91%
Volatility (1Y) Calculated over the trailing 1-year period	17.61%	12.86%	+4.75%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	22.54%	17.03%	+5.51%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	24.23%	18.07%	+6.16%

FMDGX vs. FXAIX - Expense Ratio Comparison

FMDGX has a 0.05% expense ratio, which is higher than FXAIX's 0.02% expense ratio. However, both funds are considered low-cost compared to the broader market, where average expense ratios usually range from 0.3% to 0.9%.

Dividends

FMDGX vs. FXAIX - Dividend Comparison

FMDGX's dividend yield for the trailing twelve months is around 1.84%, more than FXAIX's 1.07% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FMDGX Fidelity Mid Cap Growth Index Fund	1.84%	1.85%	0.47%	0.63%	0.81%	6.43%	0.36%	0.29%	0.00%	0.00%	0.00%	0.00%
FXAIX Fidelity 500 Index Fund	1.07%	1.11%	1.25%	1.45%	1.69%	1.22%	1.60%	2.06%	2.72%	1.97%	2.52%	2.83%

Frequently Asked Questions

Can I hold both FMDGX and FXAIX in my portfolio?

FMDGX and FXAIX have a correlation of 0.81, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, FMDGX or FXAIX?

FMDGX has higher volatility (5.15%) compared to FXAIX (3.44%). In terms of maximum drawdown, FMDGX dropped -38.59% vs FXAIX's -33.79%.

Which has better risk-adjusted returns?

FXAIX currently has the higher Sharpe Ratio (1.43 vs -0.17), 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.