FLAPX vs. FDFIX

Last updated Jun 24, 2026

FLAPX (Fidelity Flex Mid Cap Index Fund) and FDFIX (Fidelity Flex 500 Index Fund) are both mutual funds - FLAPX is a Mid Cap Blend Equities fund managed by Fidelity, while FDFIX is a Large Cap Blend Equities fund tracking the Fidelity U.S. Large Cap Index. Over the past 5 years, FLAPX returned 9.55%/yr vs 13.53%/yr for FDFIX. Their correlation of 0.90 suggests significant overlap in exposure. Both charge a 0.00% expense ratio.

Performance

FLAPX vs. FDFIX - Performance Comparison

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

Returns By Period

In the year-to-date period, FLAPX achieves a 15.80% return, which is significantly higher than FDFIX's 9.64% return.

FLAPX

• 1D: 0.16%
• 1M: 2.43%
• YTD: 15.80%
• 6M: 13.68%
• 1Y: 28.69%
• 3Y*: 19.49%
• 5Y*: 9.55%
• 10Y*: —

FDFIX

• 1D: -0.38%
• 1M: 0.31%
• YTD: 9.64%
• 6M: 8.63%
• 1Y: 25.08%
• 3Y*: 21.26%
• 5Y*: 13.53%
• 10Y*: —

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

FLAPX vs. FDFIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
FLAPX Fidelity Flex Mid Cap Index Fund	15.80%	14.33%	15.30%	17.28%	-17.28%	22.59%	17.30%	30.56%	-9.10%	14.01%
FDFIX Fidelity Flex 500 Index Fund	9.64%	17.59%	25.06%	26.27%	-18.10%	28.69%	18.46%	31.47%	-4.45%	14.41%

Correlation

The correlation between FLAPX and FDFIX is 0.79, 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	0.79
Correlation (3Y) Calculated over the trailing 3-year period	0.82
Correlation (5Y) Calculated over the trailing 5-year period	0.88
Correlation (All Time) Calculated using the full available price history since Mar 9, 2017	0.90

The correlation between FLAPX and FDFIX shifts across timeframes, from 0.79 (1 year) to 0.90 (all time), reflecting how their relationship changes across market environments.

Return for Risk

FLAPX vs. FDFIX — Risk / Return Rank

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

FLAPX

FLAPX Risk / Return Rank: 57
FLAPX Sharpe Ratio Rank: 48
FLAPX Sortino Ratio Rank: 48
FLAPX Omega Ratio Rank: 44
FLAPX Calmar Ratio Rank: 76
FLAPX Martin Ratio Rank: 72

FDFIX

FDFIX Risk / Return Rank: 61
FDFIX Sharpe Ratio Rank: 60
FDFIX Sortino Ratio Rank: 54
FDFIX Omega Ratio Rank: 56
FDFIX Calmar Ratio Rank: 65
FDFIX Martin Ratio Rank: 73

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.

FLAPX vs. FDFIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity Flex Mid Cap Index Fund (FLAPX) and Fidelity Flex 500 Index Fund (FDFIX). 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.

	FLAPX	FDFIX	Difference
Sharpe ratio: Return per unit of total volatility	1.88	2.10	-0.22
Sortino ratio: Return per unit of downside risk	2.68	2.83	-0.15
Omega ratio: Gain probability vs. loss probability	1.33	1.38	-0.05
Calmar ratio: Return relative to maximum drawdown	3.25	2.95	+0.31
Martin ratio: Return relative to average drawdown	12.82	12.98	-0.17

FLAPX vs. FDFIX - Sharpe Ratio Comparison

The current FLAPX Sharpe Ratio is 1.88, which is comparable to the FDFIX Sharpe Ratio of 2.10. The chart below compares the historical Sharpe Ratios of FLAPX and FDFIX, 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

FLAPX vs. FDFIX - Drawdown Comparison

The maximum FLAPX drawdown since its inception was -40.31%, which is greater than FDFIX's maximum drawdown of -33.77%. Use the drawdown chart below to compare losses from any high point for FLAPX and FDFIX.

Drawdown Indicators

	FLAPX	FDFIX	Difference
Max Drawdown Largest peak-to-trough decline	-40.31%	-33.77%	-6.54%
Max Drawdown (1Y) Largest decline over 1 year	-9.21%	-8.99%	-0.22%
Max Drawdown (3Y) Largest decline over 3 years	-21.02%	-18.76%	-2.26%
Max Drawdown (5Y) Largest decline over 5 years	-26.09%	-24.51%	-1.58%
Current Drawdown Current decline from peak	-0.48%	-1.70%	+1.22%
Average Drawdown Average peak-to-trough decline	-6.09%	-4.56%	-1.53%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.33%	2.03%	+0.30%

Volatility

FLAPX vs. FDFIX - Volatility Comparison

Fidelity Flex Mid Cap Index Fund (FLAPX) and Fidelity Flex 500 Index Fund (FDFIX) have volatilities of 4.60% and 4.81%, 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

	FLAPX	FDFIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	4.60%	4.81%	-0.21%
Volatility (6M) Calculated over the trailing 6-month period	12.02%	10.00%	+2.02%
Volatility (1Y) Calculated over the trailing 1-year period	15.94%	12.64%	+3.30%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	18.65%	17.05%	+1.60%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	19.94%	18.59%	+1.35%

FLAPX vs. FDFIX - Expense Ratio Comparison

FLAPX has a 0.00% expense ratio, which is lower than FDFIX's 0.00% expense ratio. Despite the difference, both funds are considered low-cost compared to the broader market, where average expense ratios usually range from 0.3% to 0.9%.

Dividends

FLAPX vs. FDFIX - Dividend Comparison

FLAPX has not paid dividends to shareholders, while FDFIX's dividend yield for the trailing twelve months is around 1.04%.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017
FDFIX Fidelity Flex 500 Index Fund	1.04%	1.11%	1.26%	1.48%	1.70%	1.27%	1.52%	1.78%	2.16%	0.50%
FLAPX Fidelity Flex Mid Cap Index Fund	0.00%	0.00%	1.08%	1.99%	1.82%	2.83%	2.16%	2.18%	2.24%	0.44%

Frequently Asked Questions

Can I hold both FLAPX and FDFIX in my portfolio?

FLAPX and FDFIX have a correlation of 0.79, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, FLAPX or FDFIX?

FDFIX has higher volatility (4.81%) compared to FLAPX (4.60%). In terms of maximum drawdown, FLAPX dropped -40.31% vs FDFIX's -33.77%.

Which has better risk-adjusted returns?

FDFIX currently has the higher Sharpe Ratio (2.10 vs 1.88), 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.