FMSAX vs. FXNAX

Last updated Jun 6, 2026

FMSAX (Fidelity Advisor Mortgage Securities Fund Class M) and FXNAX (Fidelity U.S. Bond Index Fund) are both Total Bond Market funds from Fidelity. Over the past 10 years, FMSAX returned 0.87%/yr vs 1.51%/yr for FXNAX. Their correlation of 0.88 suggests significant overlap in exposure. FMSAX charges 0.79%/yr vs 0.03%/yr for FXNAX.

Performance

FMSAX vs. FXNAX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Fidelity Advisor Mortgage Securities Fund Class M (FMSAX) 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, FMSAX achieves a 0.72% return, which is significantly higher than FXNAX's 0.31% return. Over the past 10 years, FMSAX has underperformed FXNAX with an annualized return of 0.87%, while FXNAX has yielded a comparatively higher 1.51% annualized return.

FMSAX

• 1D: 0.20%
• 1M: -0.11%
• YTD: 0.72%
• 6M: 1.09%
• 1Y: 6.29%
• 3Y*: 3.77%
• 5Y*: -0.34%
• 10Y*: 0.87%

FXNAX

• 1D: 0.10%
• 1M: -0.16%
• YTD: 0.31%
• 6M: 0.53%
• 1Y: 4.86%
• 3Y*: 3.98%
• 5Y*: 0.04%
• 10Y*: 1.51%

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

FMSAX vs. FXNAX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
FMSAX Fidelity Advisor Mortgage Securities Fund Class M	0.72%	7.91%	0.07%	4.27%	-12.80%	-1.52%	4.05%	6.04%	0.34%	2.00%
FXNAX Fidelity U.S. Bond Index Fund	0.31%	7.14%	1.35%	5.82%	-13.55%	-2.10%	7.63%	8.50%	0.04%	3.50%

Correlation

The correlation between FMSAX and FXNAX is 0.95 - 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	0.95
Correlation (3Y) Calculated over the trailing 3-year period	0.96
Correlation (5Y) Calculated over the trailing 5-year period	0.94
Correlation (10Y) Calculated over the trailing 10-year period	0.90
Correlation (All Time) Calculated using the full available price history since May 5, 2011	0.88

The correlation between FMSAX and FXNAX has been stable across timeframes, ranging from 0.88 to 0.96 - a consistent structural relationship.

Return for Risk

FMSAX vs. FXNAX — Risk / Return Rank

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

FMSAX

FMSAX Risk / Return Rank: 31
FMSAX Sharpe Ratio Rank: 31
FMSAX Sortino Ratio Rank: 32
FMSAX Omega Ratio Rank: 29
FMSAX Calmar Ratio Rank: 33
FMSAX Martin Ratio Rank: 31

FXNAX

FXNAX Risk / Return Rank: 19
FXNAX Sharpe Ratio Rank: 19
FXNAX Sortino Ratio Rank: 19
FXNAX Omega Ratio Rank: 18
FXNAX Calmar Ratio Rank: 21
FXNAX Martin Ratio Rank: 19

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.

FMSAX vs. FXNAX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity Advisor Mortgage Securities Fund Class M (FMSAX) 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.

	FMSAX	FXNAX	Difference
Sharpe ratio: Return per unit of total volatility	1.52	1.19	+0.32
Sortino ratio: Return per unit of downside risk	2.26	1.79	+0.47
Omega ratio: Gain probability vs. loss probability	1.27	1.21	+0.06
Calmar ratio: Return relative to maximum drawdown	2.08	1.59	+0.49
Martin ratio: Return relative to average drawdown	6.79	4.82	+1.97
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

FMSAX vs. FXNAX - Sharpe Ratio Comparison

The current FMSAX Sharpe Ratio is 1.52, which is comparable to the FXNAX Sharpe Ratio of 1.19. The chart below compares the historical Sharpe Ratios of FMSAX 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

	FMSAX	FXNAX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.52	1.19	+0.32
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	-0.05	0.01	-0.06
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.17	0.30	-0.13
Sharpe Ratio (All Time) Calculated using the full available price history	0.79	0.45	+0.33

Drawdowns

FMSAX vs. FXNAX - Drawdown Comparison

The maximum FMSAX drawdown since its inception was -19.47%, roughly equal to the maximum FXNAX drawdown of -19.51%. Use the drawdown chart below to compare losses from any high point for FMSAX and FXNAX.

Drawdown Indicators

	FMSAX	FXNAX	Difference
Max Drawdown Largest peak-to-trough decline	-19.47%	-19.51%	+0.04%
Max Drawdown (1Y) Largest decline over 1 year	-2.88%	-2.94%	+0.06%
Max Drawdown (3Y) Largest decline over 3 years	-8.14%	-6.16%	-1.98%
Max Drawdown (5Y) Largest decline over 5 years	-19.21%	-18.54%	-0.67%
Max Drawdown (10Y) Largest decline over 10 years	-19.47%	-19.51%	+0.04%
Current Drawdown Current decline from peak	-2.69%	-2.98%	+0.29%
Average Drawdown Average peak-to-trough decline	-2.03%	-3.86%	+1.83%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.88%	0.97%	-0.09%

Volatility

FMSAX vs. FXNAX - Volatility Comparison

Fidelity Advisor Mortgage Securities Fund Class M (FMSAX) has a higher volatility of 1.43% compared to Fidelity U.S. Bond Index Fund (FXNAX) at 1.36%. This indicates that FMSAX's price experiences larger fluctuations and is considered to be riskier than FXNAX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	FMSAX	FXNAX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.43%	1.36%	+0.07%
Volatility (6M) Calculated over the trailing 6-month period	2.77%	2.80%	-0.03%
Volatility (1Y) Calculated over the trailing 1-year period	3.99%	3.96%	+0.03%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	6.79%	6.07%	+0.72%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	5.12%	5.00%	+0.12%

FMSAX vs. FXNAX - Expense Ratio Comparison

FMSAX has a 0.79% expense ratio, which is higher than FXNAX's 0.03% expense ratio.

Dividends

FMSAX vs. FXNAX - Dividend Comparison

FMSAX's dividend yield for the trailing twelve months is around 3.55%, less than FXNAX's 3.71% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FMSAX Fidelity Advisor Mortgage Securities Fund Class M	3.55%	3.57%	3.19%	2.92%	1.13%	0.48%	2.05%	2.25%	2.22%	2.26%	2.27%	1.73%
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 FMSAX and FXNAX in my portfolio?

With a correlation of 0.95, FMSAX 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, FMSAX or FXNAX?

FMSAX has higher volatility (1.43%) compared to FXNAX (1.36%). In terms of maximum drawdown, FMSAX dropped -19.47% vs FXNAX's -19.51%.

Which has better risk-adjusted returns?

FMSAX currently has the higher Sharpe Ratio (1.52 vs 1.19), 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.