FSMTX vs. FXNAX

Last updated Jun 4, 2026

FSMTX (Fidelity SAI Total Bond Fund) and FXNAX (Fidelity U.S. Bond Index Fund) are both Total Bond Market funds from Fidelity. Over the past 5 years, FSMTX returned 1.02%/yr vs 0.12%/yr for FXNAX. With a 0.96 correlation, they move nearly in lockstep. FSMTX charges 0.30%/yr vs 0.03%/yr for FXNAX.

Performance

FSMTX vs. FXNAX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Fidelity SAI Total Bond Fund (FSMTX) 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, FSMTX achieves a 0.57% return, which is significantly higher than FXNAX's 0.40% return.

FSMTX

• 1D: 0.00%
• 1M: 0.48%
• YTD: 0.57%
• 6M: 0.55%
• 1Y: 5.80%
• 3Y*: 5.18%
• 5Y*: 1.02%
• 10Y*: —

FXNAX

• 1D: 0.00%
• 1M: 0.51%
• YTD: 0.40%
• 6M: 0.34%
• 1Y: 5.37%
• 3Y*: 4.02%
• 5Y*: 0.12%
• 10Y*: 1.51%

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

FSMTX vs. FXNAX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018
FSMTX Fidelity SAI Total Bond Fund	0.57%	7.65%	2.93%	7.33%	-13.30%	-0.30%	8.13%	9.87%	1.41%
FXNAX Fidelity U.S. Bond Index Fund	0.40%	7.14%	1.35%	5.82%	-13.55%	-2.10%	7.63%	8.50%	2.48%

Correlation

The correlation between FSMTX and FXNAX is 0.96 - these two move nearly in lockstep. At this level, holding both provides almost no diversification benefit. If you already own one, adding the other does little to reduce portfolio risk.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.96
Correlation (3Y) Calculated over the trailing 3-year period	0.97
Correlation (5Y) Calculated over the trailing 5-year period	0.97
Correlation (All Time) Calculated using the full available price history since Nov 1, 2018	0.96

The correlation between FSMTX and FXNAX has been stable across timeframes, ranging from 0.96 to 0.97 - a consistent structural relationship.

Return for Risk

FSMTX vs. FXNAX — Risk / Return Rank

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

FSMTX

FSMTX Risk / Return Rank: 28
FSMTX Sharpe Ratio Rank: 28
FSMTX Sortino Ratio Rank: 30
FSMTX Omega Ratio Rank: 27
FSMTX Calmar Ratio Rank: 31
FSMTX Martin Ratio Rank: 25

FXNAX

FXNAX Risk / Return Rank: 23
FXNAX Sharpe Ratio Rank: 23
FXNAX Sortino Ratio Rank: 24
FXNAX Omega Ratio Rank: 22
FXNAX Calmar Ratio Rank: 24
FXNAX Martin Ratio Rank: 21

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.

FSMTX vs. FXNAX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity SAI Total Bond Fund (FSMTX) 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.

	FSMTX	FXNAX	Difference
Sharpe ratio: Return per unit of total volatility	1.52	1.36	+0.16
Sortino ratio: Return per unit of downside risk	2.29	2.06	+0.24
Omega ratio: Gain probability vs. loss probability	1.27	1.24	+0.03
Calmar ratio: Return relative to maximum drawdown	2.09	1.83	+0.26
Martin ratio: Return relative to average drawdown	6.19	5.61	+0.59
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

FSMTX vs. FXNAX - Sharpe Ratio Comparison

The current FSMTX Sharpe Ratio is 1.52, which is comparable to the FXNAX Sharpe Ratio of 1.36. The chart below compares the historical Sharpe Ratios of FSMTX 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.

Sharpe Ratios by Period

	FSMTX	FXNAX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.52	1.36	+0.16
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.18	0.02	+0.16
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	—	0.30	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.57	0.45	+0.11

Drawdowns

FSMTX vs. FXNAX - Drawdown Comparison

The maximum FSMTX drawdown since its inception was -17.89%, smaller than the maximum FXNAX drawdown of -19.51%. Use the drawdown chart below to compare losses from any high point for FSMTX and FXNAX.

Drawdown Indicators

	FSMTX	FXNAX	Difference
Max Drawdown Largest peak-to-trough decline	-17.89%	-19.51%	+1.62%
Max Drawdown (1Y) Largest decline over 1 year	-2.86%	-2.94%	+0.08%
Max Drawdown (3Y) Largest decline over 3 years	-5.85%	-6.16%	+0.31%
Max Drawdown (5Y) Largest decline over 5 years	-17.89%	-18.54%	+0.65%
Max Drawdown (10Y) Largest decline over 10 years	—	-19.51%	—
Current Drawdown Current decline from peak	-1.29%	-2.89%	+1.60%
Average Drawdown Average peak-to-trough decline	-4.47%	-3.87%	-0.60%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.96%	0.96%	0.00%

Volatility

FSMTX vs. FXNAX - Volatility Comparison

Fidelity SAI Total Bond Fund (FSMTX) and Fidelity U.S. Bond Index Fund (FXNAX) have volatilities of 1.36% and 1.41%, 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

	FSMTX	FXNAX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.36%	1.41%	-0.05%
Volatility (6M) Calculated over the trailing 6-month period	2.76%	2.82%	-0.06%
Volatility (1Y) Calculated over the trailing 1-year period	3.93%	3.97%	-0.04%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	5.70%	6.07%	-0.37%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	5.22%	5.01%	+0.21%

FSMTX vs. FXNAX - Expense Ratio Comparison

FSMTX has a 0.30% expense ratio, which is higher than FXNAX's 0.03% expense ratio.

Dividends

FSMTX vs. FXNAX - Dividend Comparison

FSMTX's dividend yield for the trailing twelve months is around 4.56%, more than FXNAX's 3.71% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FSMTX Fidelity SAI Total Bond Fund	4.56%	4.56%	4.70%	4.29%	2.59%	2.74%	5.36%	4.93%	0.62%	0.00%	0.00%	0.00%
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%

Frequently Asked Questions

Can I hold both FSMTX and FXNAX in my portfolio?

With a correlation of 0.96, FSMTX 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, FSMTX or FXNAX?

FXNAX has higher volatility (1.41%) compared to FSMTX (1.36%). In terms of maximum drawdown, FSMTX dropped -17.89% vs FXNAX's -19.51%.

Which has better risk-adjusted returns?

FSMTX currently has the higher Sharpe Ratio (1.52 vs 1.36), 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.