SSFDX vs. FXNAX

Last updated Jun 23, 2026

SSFDX (State Street Aggregate Bond Index Fund) and FXNAX (Fidelity U.S. Bond Index Fund) are both mutual funds - SSFDX is a Intermediate Core Bond fund managed by State Street, while FXNAX is a Total Bond Market fund tracking the Bloomberg U.S. Aggregate Bond Index. Over the past 10 years, SSFDX returned 1.45%/yr vs 1.50%/yr for FXNAX. Their correlation of 0.93 suggests significant overlap in exposure. SSFDX charges 0.23%/yr vs 0.03%/yr for FXNAX.

Performance

SSFDX vs. FXNAX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in State Street Aggregate Bond Index Fund (SSFDX) and Fidelity U.S. Bond Index Fund (FXNAX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, SSFDX achieves a 0.62% return, which is significantly higher than FXNAX's 0.40% return. Both investments have delivered pretty close results over the past 10 years, with SSFDX having a 1.45% annualized return and FXNAX not far ahead at 1.50%.

SSFDX

• 1D: 0.27%
• 1M: 0.90%
• YTD: 0.62%
• 6M: 0.76%
• 1Y: 4.75%
• 3Y*: 3.90%
• 5Y*: -0.14%
• 10Y*: 1.45%

FXNAX

• 1D: 0.19%
• 1M: 0.90%
• YTD: 0.40%
• 6M: 0.72%
• 1Y: 4.76%
• 3Y*: 4.02%
• 5Y*: -0.06%
• 10Y*: 1.50%

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

SSFDX vs. FXNAX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
SSFDX State Street Aggregate Bond Index Fund	0.62%	6.80%	1.36%	5.39%	-13.36%	-1.98%	7.57%	8.98%	-0.20%	3.29%
FXNAX Fidelity U.S. Bond Index Fund	0.40%	7.14%	1.35%	5.82%	-13.55%	-2.10%	7.63%	8.50%	0.04%	3.50%

Correlation

The correlation between SSFDX and FXNAX 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	0.93
Correlation (All Time) Calculated using the full available price history since Sep 22, 2014	0.93

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

Return for Risk

SSFDX vs. FXNAX — Risk / Return Rank

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

SSFDX

SSFDX Risk / Return Rank: 24
SSFDX Sharpe Ratio Rank: 24
SSFDX Sortino Ratio Rank: 25
SSFDX Omega Ratio Rank: 23
SSFDX Calmar Ratio Rank: 25
SSFDX Martin Ratio Rank: 22

FXNAX

FXNAX Risk / Return Rank: 21
FXNAX Sharpe Ratio Rank: 21
FXNAX Sortino Ratio Rank: 22
FXNAX Omega Ratio Rank: 20
FXNAX Calmar Ratio Rank: 22
FXNAX Martin Ratio Rank: 20

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.

SSFDX vs. FXNAX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for State Street Aggregate Bond Index Fund (SSFDX) and Fidelity U.S. Bond Index Fund (FXNAX). 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.

	SSFDX	FXNAX	Difference
Sharpe ratio: Return per unit of total volatility	1.31	1.22	+0.09
Sortino ratio: Return per unit of downside risk	1.96	1.85	+0.11
Omega ratio: Gain probability vs. loss probability	1.23	1.22	+0.01
Calmar ratio: Return relative to maximum drawdown	1.75	1.62	+0.13
Martin ratio: Return relative to average drawdown	5.03	4.68	+0.35

SSFDX vs. FXNAX - Sharpe Ratio Comparison

The current SSFDX Sharpe Ratio is 1.31, which is comparable to the FXNAX Sharpe Ratio of 1.22. The chart below compares the historical Sharpe Ratios of SSFDX and FXNAX, 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

SSFDX vs. FXNAX - Drawdown Comparison

The maximum SSFDX drawdown since its inception was -26.93%, which is greater than FXNAX's maximum drawdown of -19.51%. Use the drawdown chart below to compare losses from any high point for SSFDX and FXNAX.

Drawdown Indicators

	SSFDX	FXNAX	Difference
Max Drawdown Largest peak-to-trough decline	-26.93%	-19.51%	-7.42%
Max Drawdown (1Y) Largest decline over 1 year	-2.75%	-2.94%	+0.19%
Max Drawdown (3Y) Largest decline over 3 years	-6.13%	-6.16%	+0.03%
Max Drawdown (5Y) Largest decline over 5 years	-18.19%	-18.54%	+0.35%
Max Drawdown (10Y) Largest decline over 10 years	-26.93%	-19.51%	-7.42%
Current Drawdown Current decline from peak	-3.06%	-2.89%	-0.17%
Average Drawdown Average peak-to-trough decline	-4.66%	-3.86%	-0.80%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.96%	1.02%	-0.06%

Volatility

SSFDX vs. FXNAX - Volatility Comparison

The current volatility for State Street Aggregate Bond Index Fund (SSFDX) is 1.14%, while Fidelity U.S. Bond Index Fund (FXNAX) has a volatility of 1.23%. This indicates that SSFDX experiences smaller price fluctuations and is considered to be less risky than FXNAX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	SSFDX	FXNAX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.14%	1.23%	-0.09%
Volatility (6M) Calculated over the trailing 6-month period	2.72%	2.89%	-0.17%
Volatility (1Y) Calculated over the trailing 1-year period	3.67%	3.90%	-0.23%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	5.93%	6.08%	-0.15%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	14.11%	5.01%	+9.10%

SSFDX vs. FXNAX - Expense Ratio Comparison

SSFDX has a 0.23% expense ratio, which is higher than FXNAX's 0.03% 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

SSFDX vs. FXNAX - Dividend Comparison

SSFDX's dividend yield for the trailing twelve months is around 4.10%, more than FXNAX's 3.71% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FXNAX Fidelity U.S. Bond Index Fund	3.71%	3.58%	3.40%	3.15%	1.81%	1.74%	2.92%	2.68%	2.74%	2.57%	2.76%	2.52%
SSFDX State Street Aggregate Bond Index Fund	4.10%	3.64%	3.59%	2.95%	2.27%	3.12%	3.00%	3.15%	2.79%	2.43%	2.19%	4.63%

Frequently Asked Questions

Can I hold both SSFDX and FXNAX in my portfolio?

With a correlation of 0.93, SSFDX and FXNAX 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, SSFDX or FXNAX?

FXNAX has higher volatility (1.23%) compared to SSFDX (1.14%). In terms of maximum drawdown, SSFDX dropped -26.93% vs FXNAX's -19.51%.

Which has better risk-adjusted returns?

SSFDX currently has the higher Sharpe Ratio (1.31 vs 1.22), 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.