FMSAX vs. FNSOX

Last updated Jun 23, 2026

FMSAX (Fidelity Advisor Mortgage Securities Fund Class M) and FNSOX (Fidelity Short-Term Bond Index Fund) are both Total Bond Market funds from Fidelity. Over the past 5 years, FMSAX returned -0.31%/yr vs 1.61%/yr for FNSOX. Their correlation of 0.80 suggests significant overlap in exposure. FMSAX charges 0.79%/yr vs 0.03%/yr for FNSOX.

Performance

FMSAX vs. FNSOX - 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 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, FMSAX achieves a 0.72% return, which is significantly higher than FNSOX's 0.17% return.

FMSAX

• 1D: 0.20%
• 1M: 0.80%
• YTD: 0.72%
• 6M: 0.99%
• 1Y: 5.85%
• 3Y*: 3.66%
• 5Y*: -0.31%
• 10Y*: 0.86%

FNSOX

• 1D: 0.10%
• 1M: 0.27%
• YTD: 0.17%
• 6M: 0.52%
• 1Y: 3.36%
• 3Y*: 4.52%
• 5Y*: 1.61%
• 10Y*: —

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

FMSAX vs. FNSOX - 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%	0.24%
FNSOX Fidelity Short-Term Bond Index Fund	0.17%	6.01%	3.90%	4.90%	-5.76%	-1.25%	4.28%	4.95%	1.14%	-0.22%

Correlation

The correlation between FMSAX and FNSOX is 0.84, 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	0.84
Correlation (3Y) Calculated over the trailing 3-year period	0.84
Correlation (5Y) Calculated over the trailing 5-year period	0.85
Correlation (All Time) Calculated using the full available price history since Oct 31, 2017	0.80

The correlation between FMSAX and FNSOX has been stable across timeframes, ranging from 0.80 to 0.85 - a consistent structural relationship.

Return for Risk

FMSAX vs. FNSOX — 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: 34
FMSAX Omega Ratio Rank: 31
FMSAX Calmar Ratio Rank: 33
FMSAX Martin Ratio Rank: 29

FNSOX

FNSOX Risk / Return Rank: 40
FNSOX Sharpe Ratio Rank: 36
FNSOX Sortino Ratio Rank: 45
FNSOX Omega Ratio Rank: 43
FNSOX Calmar Ratio Rank: 40
FNSOX Martin Ratio Rank: 34

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. FNSOX - 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 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.

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.

	FMSAX	FNSOX	Difference
Sharpe ratio: Return per unit of total volatility	1.50	1.62	-0.12
Sortino ratio: Return per unit of downside risk	2.24	2.60	-0.36
Omega ratio: Gain probability vs. loss probability	1.27	1.33	-0.06
Calmar ratio: Return relative to maximum drawdown	2.04	2.29	-0.24
Martin ratio: Return relative to average drawdown	6.33	7.15	-0.82

FMSAX vs. FNSOX - Sharpe Ratio Comparison

The current FMSAX Sharpe Ratio is 1.50, which is comparable to the FNSOX Sharpe Ratio of 1.62. The chart below compares the historical Sharpe Ratios of FMSAX 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.

Drawdowns

FMSAX vs. FNSOX - Drawdown Comparison

The maximum FMSAX drawdown since its inception was -19.47%, which is greater than FNSOX's maximum drawdown of -8.92%. Use the drawdown chart below to compare losses from any high point for FMSAX and FNSOX.

Drawdown Indicators

	FMSAX	FNSOX	Difference
Max Drawdown Largest peak-to-trough decline	-19.47%	-8.92%	-10.55%
Max Drawdown (1Y) Largest decline over 1 year	-2.88%	-1.47%	-1.41%
Max Drawdown (3Y) Largest decline over 3 years	-8.14%	-1.51%	-6.63%
Max Drawdown (5Y) Largest decline over 5 years	-19.21%	-8.77%	-10.44%
Max Drawdown (10Y) Largest decline over 10 years	-19.47%	—	—
Current Drawdown Current decline from peak	-2.69%	-0.80%	-1.89%
Average Drawdown Average peak-to-trough decline	-2.03%	-1.73%	-0.30%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.93%	0.47%	+0.46%

Volatility

FMSAX vs. FNSOX - Volatility Comparison

Fidelity Advisor Mortgage Securities Fund Class M (FMSAX) has a higher volatility of 1.27% compared to Fidelity Short-Term Bond Index Fund (FNSOX) at 0.73%. This indicates that FMSAX'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

	FMSAX	FNSOX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.27%	0.73%	+0.54%
Volatility (6M) Calculated over the trailing 6-month period	2.86%	1.56%	+1.30%
Volatility (1Y) Calculated over the trailing 1-year period	3.91%	2.08%	+1.83%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	6.80%	2.89%	+3.91%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	5.13%	2.47%	+2.66%

FMSAX vs. FNSOX - Expense Ratio Comparison

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

Dividends

FMSAX vs. FNSOX - Dividend Comparison

FMSAX's dividend yield for the trailing twelve months is around 3.55%, which matches FNSOX's 3.53% 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%
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%

Frequently Asked Questions

Can I hold both FMSAX and FNSOX in my portfolio?

FMSAX and FNSOX have a correlation of 0.84, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, FMSAX or FNSOX?

FMSAX has higher volatility (1.27%) compared to FNSOX (0.73%). In terms of maximum drawdown, FMSAX dropped -19.47% vs FNSOX's -8.92%.

Which has better risk-adjusted returns?

FNSOX currently has the higher Sharpe Ratio (1.62 vs 1.50), 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.