SSFEX vs. FNSOX

Last updated Jun 5, 2026

SSFEX (State Street Aggregate Bond Index Fund Class K) and FNSOX (Fidelity Short-Term Bond Index Fund) are both Total Bond Market funds. Over the past 5 years, SSFEX returned -0.01%/yr vs 1.58%/yr for FNSOX. A 0.78 correlation means they provide meaningful diversification when combined. Both charge a 0.03% expense ratio.

Performance

SSFEX vs. FNSOX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in State Street Aggregate Bond Index Fund Class K (SSFEX) and Fidelity Short-Term Bond Index Fund (FNSOX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, SSFEX achieves a 0.21% return, which is significantly lower than FNSOX's 0.27% return.

SSFEX

• 1D: -0.21%
• 1M: 0.08%
• YTD: 0.21%
• 6M: 0.32%
• 1Y: 4.54%
• 3Y*: 3.82%
• 5Y*: -0.01%
• 10Y*: -19.32%

FNSOX

• 1D: -0.10%
• 1M: -0.03%
• YTD: 0.27%
• 6M: 0.62%
• 1Y: 3.46%
• 3Y*: 4.44%
• 5Y*: 1.58%
• 10Y*: —

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

SSFEX vs. FNSOX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
SSFEX State Street Aggregate Bond Index Fund Class K	0.21%	6.80%	1.35%	5.61%	-13.19%	-1.78%	-89.22%	9.45%	-0.10%	0.31%
FNSOX Fidelity Short-Term Bond Index Fund	0.27%	6.01%	3.90%	4.90%	-5.76%	-1.25%	4.28%	4.95%	1.14%	-0.22%

Correlation

The correlation between SSFEX and FNSOX is 0.78, 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	0.78
Correlation (3Y) Calculated over the trailing 3-year period	0.80
Correlation (5Y) Calculated over the trailing 5-year period	0.83
Correlation (All Time) Calculated using the full available price history since Nov 1, 2017	0.78

The correlation between SSFEX and FNSOX has been stable across timeframes, ranging from 0.78 to 0.83 - a consistent structural relationship.

Return for Risk

SSFEX vs. FNSOX — Risk / Return Rank

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

SSFEX

SSFEX Risk / Return Rank: 25
SSFEX Sharpe Ratio Rank: 24
SSFEX Sortino Ratio Rank: 26
SSFEX Omega Ratio Rank: 23
SSFEX Calmar Ratio Rank: 27
SSFEX Martin Ratio Rank: 24

FNSOX

FNSOX Risk / Return Rank: 42
FNSOX Sharpe Ratio Rank: 38
FNSOX Sortino Ratio Rank: 47
FNSOX Omega Ratio Rank: 44
FNSOX Calmar Ratio Rank: 43
FNSOX Martin Ratio Rank: 38

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.

SSFEX vs. FNSOX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for State Street Aggregate Bond Index Fund Class K (SSFEX) and Fidelity Short-Term Bond Index Fund (FNSOX). 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.

	SSFEX	FNSOX	Difference
Sharpe ratio: Return per unit of total volatility	1.39	1.78	-0.39
Sortino ratio: Return per unit of downside risk	2.08	2.90	-0.82
Omega ratio: Gain probability vs. loss probability	1.25	1.36	-0.11
Calmar ratio: Return relative to maximum drawdown	1.89	2.50	-0.61
Martin ratio: Return relative to average drawdown	5.75	8.25	-2.50
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

SSFEX vs. FNSOX - Sharpe Ratio Comparison

The current SSFEX Sharpe Ratio is 1.39, which is comparable to the FNSOX Sharpe Ratio of 1.78. The chart below compares the historical Sharpe Ratios of SSFEX and FNSOX, 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

	SSFEX	FNSOX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.39	1.78	-0.39
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	-0.00	0.55	-0.55
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	-0.61	—	—
Sharpe Ratio (All Time) Calculated using the full available price history	-0.55	0.83	-1.39

Drawdowns

SSFEX vs. FNSOX - Drawdown Comparison

The maximum SSFEX drawdown since its inception was -92.70%, which is greater than FNSOX's maximum drawdown of -8.92%. Use the drawdown chart below to compare losses from any high point for SSFEX and FNSOX.

Drawdown Indicators

	SSFEX	FNSOX	Difference
Max Drawdown Largest peak-to-trough decline	-92.70%	-8.92%	-83.78%
Max Drawdown (1Y) Largest decline over 1 year	-2.75%	-1.47%	-1.28%
Max Drawdown (3Y) Largest decline over 3 years	-6.09%	-1.51%	-4.58%
Max Drawdown (5Y) Largest decline over 5 years	-17.99%	-8.77%	-9.22%
Max Drawdown (10Y) Largest decline over 10 years	-92.70%	—	—
Current Drawdown Current decline from peak	-90.07%	-0.70%	-89.37%
Average Drawdown Average peak-to-trough decline	-48.01%	-1.73%	-46.28%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.90%	0.45%	+0.45%

Volatility

SSFEX vs. FNSOX - Volatility Comparison

State Street Aggregate Bond Index Fund Class K (SSFEX) has a higher volatility of 1.27% compared to Fidelity Short-Term Bond Index Fund (FNSOX) at 0.65%. This indicates that SSFEX's price experiences larger fluctuations and is considered to be riskier than FNSOX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	SSFEX	FNSOX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.27%	0.65%	+0.62%
Volatility (6M) Calculated over the trailing 6-month period	2.63%	1.51%	+1.12%
Volatility (1Y) Calculated over the trailing 1-year period	3.74%	2.07%	+1.67%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	5.93%	2.89%	+3.04%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	31.83%	2.47%	+29.36%

SSFEX vs. FNSOX - Expense Ratio Comparison

Both SSFEX and FNSOX have an expense ratio of 0.03%, making them cost-effective options compared to the broader market, where average expense ratios typically range from 0.3% to 0.9%.

Dividends

SSFEX vs. FNSOX - Dividend Comparison

SSFEX's dividend yield for the trailing twelve months is around 4.13%, more than FNSOX's 3.53% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FNSOX Fidelity Short-Term Bond Index Fund	3.53%	3.22%	2.80%	1.74%	0.81%	0.80%	1.54%	2.61%	2.04%	0.34%	0.00%	0.00%
SSFEX State Street Aggregate Bond Index Fund Class K	4.13%	3.66%	3.76%	3.14%	2.48%	3.32%	9.59%	3.56%	2.79%	2.43%	2.19%	4.67%

Frequently Asked Questions

Can I hold both SSFEX and FNSOX in my portfolio?

SSFEX and FNSOX have a correlation of 0.78, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, SSFEX or FNSOX?

SSFEX has higher volatility (1.27%) compared to FNSOX (0.65%). In terms of maximum drawdown, SSFEX dropped -92.70% vs FNSOX's -8.92%.

Which has better risk-adjusted returns?

FNSOX currently has the higher Sharpe Ratio (1.78 vs 1.39), 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.