FIFZX vs. DOXIX

Last updated Jun 25, 2026

FIFZX (Fidelity Series Bond Index Fund) and DOXIX (Dodge & Cox Income Fund Class X) are both mutual funds - FIFZX is a Total Bond Market fund managed by Fidelity, while DOXIX is a Intermediate Core-Plus Bond fund actively managed by Dodge & Cox. Over the past 3 years, FIFZX returned 3.94%/yr vs 5.19%/yr for DOXIX. With a 0.96 correlation, they move nearly in lockstep. FIFZX charges 0.00%/yr vs 0.33%/yr for DOXIX.

Performance

FIFZX vs. DOXIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Fidelity Series Bond Index Fund (FIFZX) and Dodge & Cox Income Fund Class X (DOXIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, FIFZX achieves a 0.23% return, which is significantly lower than DOXIX's 0.53% return.

FIFZX

• 1D: 0.11%
• 1M: 0.68%
• YTD: 0.23%
• 6M: 0.35%
• 1Y: 4.05%
• 3Y*: 3.94%
• 5Y*: -0.05%
• 10Y*: —

DOXIX

• 1D: 0.08%
• 1M: 0.79%
• YTD: 0.53%
• 6M: 0.45%
• 1Y: 4.99%
• 3Y*: 5.19%
• 5Y*: —
• 10Y*: —

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

FIFZX vs. DOXIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022
FIFZX Fidelity Series Bond Index Fund	0.23%	7.15%	1.41%	5.54%	-3.94%
DOXIX Dodge & Cox Income Fund Class X	0.53%	8.39%	2.33%	7.75%	-2.35%

Correlation

The correlation between FIFZX and DOXIX 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	0.95
Correlation (All Time) Calculated using the full available price history since May 3, 2022	0.96

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

Return for Risk

FIFZX vs. DOXIX — Risk / Return Rank

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

FIFZX

FIFZX Risk / Return Rank: 20
FIFZX Sharpe Ratio Rank: 20
FIFZX Sortino Ratio Rank: 21
FIFZX Omega Ratio Rank: 18
FIFZX Calmar Ratio Rank: 21
FIFZX Martin Ratio Rank: 18

DOXIX

DOXIX Risk / Return Rank: 25
DOXIX Sharpe Ratio Rank: 27
DOXIX Sortino Ratio Rank: 27
DOXIX Omega Ratio Rank: 25
DOXIX Calmar Ratio Rank: 25
DOXIX Martin Ratio Rank: 22

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.

FIFZX vs. DOXIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity Series Bond Index Fund (FIFZX) and Dodge & Cox Income Fund Class X (DOXIX). 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.

	FIFZX	DOXIX	Difference
Sharpe ratio: Return per unit of total volatility	1.12	1.34	-0.21
Sortino ratio: Return per unit of downside risk	1.71	1.97	-0.27
Omega ratio: Gain probability vs. loss probability	1.20	1.24	-0.04
Calmar ratio: Return relative to maximum drawdown	1.52	1.70	-0.18
Martin ratio: Return relative to average drawdown	4.25	4.86	-0.61

FIFZX vs. DOXIX - Sharpe Ratio Comparison

The current FIFZX Sharpe Ratio is 1.12, which is comparable to the DOXIX Sharpe Ratio of 1.34. The chart below compares the historical Sharpe Ratios of FIFZX and DOXIX, 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

FIFZX vs. DOXIX - Drawdown Comparison

The maximum FIFZX drawdown since its inception was -19.27%, which is greater than DOXIX's maximum drawdown of -8.83%. Use the drawdown chart below to compare losses from any high point for FIFZX and DOXIX.

Drawdown Indicators

	FIFZX	DOXIX	Difference
Max Drawdown Largest peak-to-trough decline	-19.27%	-8.83%	-10.44%
Max Drawdown (1Y) Largest decline over 1 year	-2.91%	-3.15%	+0.24%
Max Drawdown (3Y) Largest decline over 3 years	-6.12%	-5.66%	-0.46%
Max Drawdown (5Y) Largest decline over 5 years	-18.47%	—	—
Current Drawdown Current decline from peak	-2.97%	-1.61%	-1.36%
Average Drawdown Average peak-to-trough decline	-6.67%	-1.86%	-4.81%
Ulcer Index Depth and duration of drawdowns from previous peaks	1.04%	1.10%	-0.06%

Volatility

FIFZX vs. DOXIX - Volatility Comparison

Fidelity Series Bond Index Fund (FIFZX) and Dodge & Cox Income Fund Class X (DOXIX) have volatilities of 1.18% and 1.18%, 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

	FIFZX	DOXIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.18%	1.18%	0.00%
Volatility (6M) Calculated over the trailing 6-month period	2.90%	3.01%	-0.11%
Volatility (1Y) Calculated over the trailing 1-year period	3.93%	4.01%	-0.08%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	6.08%	5.83%	+0.25%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	5.62%	5.83%	-0.21%

FIFZX vs. DOXIX - Expense Ratio Comparison

FIFZX has a 0.00% expense ratio, which is lower than DOXIX's 0.33% expense ratio.

Dividends

FIFZX vs. DOXIX - Dividend Comparison

FIFZX's dividend yield for the trailing twelve months is around 4.01%, less than DOXIX's 4.33% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019
DOXIX Dodge & Cox Income Fund Class X	4.33%	4.30%	4.32%	3.92%	2.30%	0.00%	0.00%	0.00%
FIFZX Fidelity Series Bond Index Fund	4.01%	3.87%	3.66%	3.09%	1.74%	1.42%	3.20%	1.64%

Frequently Asked Questions

Can I hold both FIFZX and DOXIX in my portfolio?

With a correlation of 0.93, FIFZX and DOXIX 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, FIFZX or DOXIX?

DOXIX has higher volatility (1.18%) compared to FIFZX (1.18%). In terms of maximum drawdown, FIFZX dropped -19.27% vs DOXIX's -8.83%.

Which has better risk-adjusted returns?

DOXIX currently has the higher Sharpe Ratio (1.34 vs 1.12), 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.