FDFIX vs. FZOLX

Last updated Jun 24, 2026

FDFIX (Fidelity Flex 500 Index Fund) and FZOLX (Fidelity SAI Low Duration Income Fund) are both mutual funds - FDFIX is a Large Cap Blend Equities fund tracking the Fidelity U.S. Large Cap Index, while FZOLX is a Ultrashort Bond fund managed by Fidelity. Over the past 5 years, FDFIX returned 13.53%/yr vs 3.51%/yr for FZOLX. At a 0.03 correlation, their price movements are largely independent. FDFIX charges 0.00%/yr vs 0.22%/yr for FZOLX.

Performance

FDFIX vs. FZOLX - Performance Comparison

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

Returns By Period

In the year-to-date period, FDFIX achieves a 9.64% return, which is significantly higher than FZOLX's 1.26% return.

FDFIX

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

FZOLX

• 1D: -0.10%
• 1M: 0.22%
• YTD: 1.26%
• 6M: 1.70%
• 1Y: 4.05%
• 3Y*: 5.21%
• 5Y*: 3.51%
• 10Y*: —

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

FDFIX vs. FZOLX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020
FDFIX Fidelity Flex 500 Index Fund	9.64%	17.59%	25.06%	26.27%	-18.10%	28.69%	11.51%
FZOLX Fidelity SAI Low Duration Income Fund	1.26%	4.85%	5.59%	5.72%	0.34%	-0.04%	0.11%

Correlation

The correlation between FDFIX and FZOLX is 0.11, which is low. Their price movements are largely independent, making them effective diversification partners.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.11
Correlation (3Y) Calculated over the trailing 3-year period	0.05
Correlation (5Y) Calculated over the trailing 5-year period	0.04
Correlation (All Time) Calculated using the full available price history since Sep 15, 2020	0.03

Return for Risk

FDFIX vs. FZOLX — Risk / Return Rank

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

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

FZOLX

FZOLX Risk / Return Rank: 99
FZOLX Sharpe Ratio Rank: 96
FZOLX Sortino Ratio Rank: 99
FZOLX Omega Ratio Rank: 99
FZOLX Calmar Ratio Rank: 99
FZOLX Martin Ratio Rank: 99

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.

FDFIX vs. FZOLX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity Flex 500 Index Fund (FDFIX) and Fidelity SAI Low Duration Income Fund (FZOLX). 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.

	FDFIX	FZOLX	Difference
Sharpe ratio: Return per unit of total volatility	2.10	3.24	-1.14
Sortino ratio: Return per unit of downside risk	2.83	9.69	-6.85
Omega ratio: Gain probability vs. loss probability	1.38	3.28	-1.90
Calmar ratio: Return relative to maximum drawdown	2.95	13.95	-11.01
Martin ratio: Return relative to average drawdown	12.98	72.13	-59.15

FDFIX vs. FZOLX - Sharpe Ratio Comparison

The current FDFIX Sharpe Ratio is 2.10, which is lower than the FZOLX Sharpe Ratio of 3.24. The chart below compares the historical Sharpe Ratios of FDFIX and FZOLX, 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

FDFIX vs. FZOLX - Drawdown Comparison

The maximum FDFIX drawdown since its inception was -33.77%, which is greater than FZOLX's maximum drawdown of -1.10%. Use the drawdown chart below to compare losses from any high point for FDFIX and FZOLX.

Drawdown Indicators

	FDFIX	FZOLX	Difference
Max Drawdown Largest peak-to-trough decline	-33.77%	-1.10%	-32.67%
Max Drawdown (1Y) Largest decline over 1 year	-8.99%	-0.30%	-8.69%
Max Drawdown (3Y) Largest decline over 3 years	-18.76%	-0.30%	-18.46%
Max Drawdown (5Y) Largest decline over 5 years	-24.51%	-1.10%	-23.41%
Current Drawdown Current decline from peak	-1.70%	-0.10%	-1.60%
Average Drawdown Average peak-to-trough decline	-4.56%	-0.13%	-4.43%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.03%	0.06%	+1.97%

Volatility

FDFIX vs. FZOLX - Volatility Comparison

Fidelity Flex 500 Index Fund (FDFIX) has a higher volatility of 4.81% compared to Fidelity SAI Low Duration Income Fund (FZOLX) at 0.37%. This indicates that FDFIX's price experiences larger fluctuations and is considered to be riskier than FZOLX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	FDFIX	FZOLX	Difference
Volatility (1M) Calculated over the trailing 1-month period	4.81%	0.37%	+4.44%
Volatility (6M) Calculated over the trailing 6-month period	10.00%	0.90%	+9.10%
Volatility (1Y) Calculated over the trailing 1-year period	12.64%	1.29%	+11.35%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	17.05%	1.22%	+15.83%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	18.59%	1.15%	+17.44%

FDFIX vs. FZOLX - Expense Ratio Comparison

FDFIX has a 0.00% expense ratio, which is lower than FZOLX's 0.22% 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

FDFIX vs. FZOLX - Dividend Comparison

FDFIX's dividend yield for the trailing twelve months is around 1.04%, less than FZOLX's 5.09% yield.

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%
FZOLX Fidelity SAI Low Duration Income Fund	5.09%	5.26%	5.15%	4.03%	1.14%	0.16%	0.01%	0.00%	0.00%	0.00%

Frequently Asked Questions

Can I hold both FDFIX and FZOLX in my portfolio?

FDFIX and FZOLX have a correlation of 0.11, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, FDFIX or FZOLX?

FDFIX has higher volatility (4.81%) compared to FZOLX (0.37%). In terms of maximum drawdown, FDFIX dropped -33.77% vs FZOLX's -1.10%.

Which has better risk-adjusted returns?

FZOLX currently has the higher Sharpe Ratio (3.24 vs 2.10), 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.