FFDKX vs. FXAIX

Last updated Jun 3, 2026

FFDKX (Fidelity Fund Class K) and FXAIX (Fidelity 500 Index Fund) are both mutual funds - FFDKX is a Large Cap Growth Equities fund managed by Fidelity, while FXAIX is a S&P 500 fund tracking the S&P 500 Index. Over the past 10 years, FFDKX returned 15.55%/yr vs 15.65%/yr for FXAIX. With a 0.96 correlation, they move nearly in lockstep. FFDKX charges 0.38%/yr vs 0.02%/yr for FXAIX.

Performance

FFDKX vs. FXAIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Fidelity Fund Class K (FFDKX) 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, FFDKX achieves a 4.50% return, which is significantly lower than FXAIX's 11.56% return. Both investments have delivered pretty close results over the past 10 years, with FFDKX having a 15.55% annualized return and FXAIX not far ahead at 15.65%.

FFDKX

• 1D: 0.40%
• 1M: 2.30%
• YTD: 4.50%
• 6M: 5.35%
• 1Y: 24.84%
• 3Y*: 21.84%
• 5Y*: 13.43%
• 10Y*: 15.55%

FXAIX

• 1D: 0.27%
• 1M: 5.24%
• YTD: 11.56%
• 6M: 11.94%
• 1Y: 29.57%
• 3Y*: 22.70%
• 5Y*: 14.17%
• 10Y*: 15.65%

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

FFDKX vs. FXAIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
FFDKX Fidelity Fund Class K	4.50%	20.13%	27.24%	31.03%	-25.81%	33.32%	26.55%	33.57%	-5.23%	23.35%
FXAIX Fidelity 500 Index Fund	11.56%	17.84%	25.01%	26.29%	-18.14%	28.71%	18.42%	31.48%	-4.43%	21.82%

Correlation

The correlation between FFDKX and FXAIX is 0.93, 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	0.93
Correlation (3Y) Calculated over the trailing 3-year period	0.94
Correlation (5Y) Calculated over the trailing 5-year period	0.96
Correlation (10Y) Calculated over the trailing 10-year period	0.95
Correlation (All Time) Calculated using the full available price history since May 5, 2011	0.96

The correlation between FFDKX and FXAIX has been stable across timeframes, ranging from 0.93 to 0.96 - a consistent structural relationship.

Return for Risk

FFDKX vs. FXAIX — Risk / Return Rank

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

FFDKX

FFDKX Risk / Return Rank: 46
FFDKX Sharpe Ratio Rank: 49
FFDKX Sortino Ratio Rank: 46
FFDKX Omega Ratio Rank: 46
FFDKX Calmar Ratio Rank: 39
FFDKX Martin Ratio Rank: 49

FXAIX

FXAIX Risk / Return Rank: 75
FXAIX Sharpe Ratio Rank: 77
FXAIX Sortino Ratio Rank: 69
FXAIX Omega Ratio Rank: 69
FXAIX Calmar Ratio Rank: 74
FXAIX Martin Ratio Rank: 84

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.

FFDKX vs. FXAIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity Fund Class K (FFDKX) 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.

	FFDKX	FXAIX	Difference
Sharpe ratio Return per unit of total volatility	2.07	2.55	-0.48
Sortino ratio Return per unit of downside risk	2.89	3.46	-0.58
Omega ratio Gain probability vs. loss probability	1.37	1.46	-0.09
Calmar ratio Return relative to maximum drawdown	2.38	3.39	-1.01
Martin ratio Return relative to average drawdown	10.08	15.86	-5.77
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

FFDKX vs. FXAIX - Sharpe Ratio Comparison

The current FFDKX Sharpe Ratio is 2.07, which is comparable to the FXAIX Sharpe Ratio of 2.55. The chart below compares the historical Sharpe Ratios of FFDKX 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.

Sharpe Ratios by Period

	FFDKX	FXAIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.07	2.55	-0.48
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.70	0.84	-0.14
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.80	0.87	-0.07
Sharpe Ratio (All Time) Calculated using the full available price history	0.54	0.82	-0.28

Drawdowns

FFDKX vs. FXAIX - Drawdown Comparison

The maximum FFDKX drawdown since its inception was -52.66%, which is greater than FXAIX's maximum drawdown of -33.79%. Use the drawdown chart below to compare losses from any high point for FFDKX and FXAIX.

Drawdown Indicators

	FFDKX	FXAIX	Difference
Max Drawdown Largest peak-to-trough decline	-52.66%	-33.79%	-18.87%
Max Drawdown (1Y) Largest decline over 1 year	-10.86%	-8.89%	-1.97%
Max Drawdown (3Y) Largest decline over 3 years	-22.41%	-18.76%	-3.65%
Max Drawdown (5Y) Largest decline over 5 years	-30.28%	-24.50%	-5.78%
Max Drawdown (10Y) Largest decline over 10 years	-30.65%	-33.79%	+3.14%
Current Drawdown Current decline from peak	0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-8.21%	-3.79%	-4.42%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.56%	1.90%	+0.66%

Volatility

FFDKX vs. FXAIX - Volatility Comparison

The current volatility for Fidelity Fund Class K (FFDKX) is 2.67%, while Fidelity 500 Index Fund (FXAIX) has a volatility of 2.82%. This indicates that FFDKX experiences smaller price fluctuations and is considered to be less risky than FXAIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	FFDKX	FXAIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	2.67%	2.82%	-0.15%
Volatility (6M) Calculated over the trailing 6-month period	9.03%	8.99%	+0.04%
Volatility (1Y) Calculated over the trailing 1-year period	12.53%	11.88%	+0.65%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	19.17%	16.91%	+2.26%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	19.43%	18.07%	+1.36%

FFDKX vs. FXAIX - Expense Ratio Comparison

FFDKX has a 0.38% expense ratio, which is higher than FXAIX's 0.02% expense ratio.

Dividends

FFDKX vs. FXAIX - Dividend Comparison

FFDKX's dividend yield for the trailing twelve months is around 1.20%, more than FXAIX's 1.03% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FFDKX Fidelity Fund Class K	1.20%	1.25%	0.00%	2.48%	0.74%	4.67%	2.77%	5.49%	7.51%	11.18%	7.12%	5.60%
FXAIX Fidelity 500 Index Fund	1.03%	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 FFDKX and FXAIX in my portfolio?

With a correlation of 0.93, FFDKX and FXAIX 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, FFDKX or FXAIX?

FXAIX has higher volatility (2.82%) compared to FFDKX (2.67%). In terms of maximum drawdown, FFDKX dropped -52.66% vs FXAIX's -33.79%.

Which has better risk-adjusted returns?

FXAIX currently has the higher Sharpe Ratio (2.55 vs 2.07), 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.