MFGSX vs. FBLTX

Last updated Aug 5, 2026

MFGSX (MFS Government Securities Fund) and FBLTX (Fidelity SAI Long-Term Treasury Bond Index Fund) are both Government Bonds funds. Over the past 10 years, MFGSX returned 0.38%/yr vs -2.42%/yr for FBLTX. Their correlation of 0.87 means they have usually moved in the same direction. MFGSX charges 0.76%/yr vs 0.03%/yr for FBLTX.

Performance

MFGSX vs. FBLTX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in MFS Government Securities Fund (MFGSX) and Fidelity SAI Long-Term Treasury Bond Index Fund (FBLTX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, MFGSX achieves a -1.25% return, which is significantly higher than FBLTX's -3.68% return. Over the past 10 years, MFGSX has outperformed FBLTX with an annualized return of 0.38%, while FBLTX has yielded a comparatively lower -2.42% annualized return.

MFGSX

• 1D: 0.24%
• 1M: -1.28%
• 6M: -1.31%
• YTD: -1.25%
• 1Y: 0.79%
• 3Y*: 2.67%
• 5Y*: -1.31%
• 10Y*: 0.38%
• ALL TIME*: 3.51%

FBLTX

• 1D: 0.32%
• 1M: -3.93%
• 6M: -3.44%
• YTD: -3.68%
• 1Y: -2.62%
• 3Y*: -1.26%
• 5Y*: -8.59%
• 10Y*: -2.42%
• ALL TIME*: -1.08%

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

Liquidity Comparison

Position	Avg. Volume Value (2W)	Avg. Volume Value (1M)	Avg. Volume Value (3M)
FBLTX Fidelity SAI Long-Term Treasury Bond Index Fund	$0.00	$0.00	$0.00
MFGSX MFS Government Securities Fund	$0.00	$0.00	$0.00

MFGSX vs. FBLTX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
MFGSX MFS Government Securities Fund	-1.25%	6.62%	-0.16%	3.28%	-12.54%	-2.18%	6.25%	6.20%	0.27%	1.93%
FBLTX Fidelity SAI Long-Term Treasury Bond Index Fund	-3.68%	4.39%	-8.05%	2.71%	-31.84%	-4.89%	18.27%	14.36%	-1.24%	9.06%

Correlation

The correlation between MFGSX and FBLTX is 0.86, meaning they have usually moved in the same direction, including during past declines.

	Correlation
Correlation (1Y) Focuses on recent behavior, but can change the most.	0.86
Correlation (3Y) Balances recent behavior with more history.	0.88
Correlation (5Y) Shows whether the relationship held over a longer period.	0.89
Correlation (10Y) Provides a long-term view across more market conditions.	0.87
Correlation (All Time) Calculated using the full available price history since Oct 16, 2015	0.87

The correlation between MFGSX and FBLTX has been stable across timeframes, ranging from 0.86 to 0.89 - a consistent structural relationship.

Return for Risk

MFGSX vs. FBLTX — Risk / Return Rank

Compare historical risk-adjusted metric ranks over the past 12 months.

MFGSX

MFGSX Risk / Return Rank: 5
MFGSX Sharpe Ratio Rank: 6
MFGSX Sortino Ratio Rank: 5
MFGSX Omega Ratio Rank: 5
MFGSX Calmar Ratio Rank: 6
MFGSX Martin Ratio Rank: 6

FBLTX

FBLTX Risk / Return Rank: 2
FBLTX Sharpe Ratio Rank: 2
FBLTX Sortino Ratio Rank: 2
FBLTX Omega Ratio Rank: 2
FBLTX Calmar Ratio Rank: 2
FBLTX Martin Ratio Rank: 1

The rank (0–100) uses a weighted average of the Sharpe, Sortino, Omega, Calmar, and Martin percentile ranks for the trailing 12 months. Higher means stronger historical risk-adjusted performance within the peer group.

MFGSX vs. FBLTX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for MFS Government Securities Fund (MFGSX) and Fidelity SAI Long-Term Treasury Bond Index Fund (FBLTX). 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.

	MFGSX	FBLTX	Difference
Sharpe ratio: Return per unit of total volatility	0.24	-0.27	+0.51
Sortino ratio: Return per unit of downside risk	0.36	-0.32	+0.68
Omega ratio: Gain probability vs. loss probability	1.04	0.96	+0.08
Calmar ratio: Return relative to maximum drawdown	0.27	-0.31	+0.58
Martin ratio: Return relative to average drawdown	0.63	-0.69	+1.32

MFGSX vs. FBLTX - Sharpe Ratio Comparison

The current MFGSX Sharpe Ratio is 0.24, which is higher than the FBLTX Sharpe Ratio of -0.27. The chart below compares the historical Sharpe Ratios of MFGSX and FBLTX, 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

MFGSX vs. FBLTX - Drawdown Comparison

The maximum MFGSX drawdown since its inception was -19.50%, smaller than the maximum FBLTX drawdown of -49.06%. Use the drawdown chart below to compare losses from any high point for MFGSX and FBLTX.

Drawdown Indicators

	MFGSX	FBLTX	Difference
Max Drawdown Largest peak-to-trough decline	-19.50%	-49.06%	+29.56%
Max Drawdown (1Y) Largest decline over 1 year	-3.39%	-8.02%	+4.63%
Max Drawdown (3Y) Largest decline over 3 years	-5.67%	-14.75%	+9.08%
Max Drawdown (5Y) Largest decline over 5 years	-17.96%	-44.19%	+26.23%
Max Drawdown (10Y) Largest decline over 10 years	-19.50%	-49.06%	+29.56%
Current Drawdown Current decline from peak	-7.95%	-43.13%	+35.18%
Average Drawdown Average peak-to-trough decline	-3.33%	-21.30%	+17.97%
Ulcer Index Depth and duration of drawdowns from previous peaks	1.44%	3.61%	-2.17%

Volatility

MFGSX vs. FBLTX - Volatility Comparison

The current volatility for MFS Government Securities Fund (MFGSX) is 0.97%, while Fidelity SAI Long-Term Treasury Bond Index Fund (FBLTX) has a volatility of 2.54%. This indicates that MFGSX experiences smaller price fluctuations and is considered to be less risky than FBLTX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	MFGSX	FBLTX	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.97%	2.54%	-1.57%
Volatility (6M) Calculated over the trailing 6-month period	3.03%	6.82%	-3.79%
Volatility (1Y) Calculated over the trailing 1-year period	3.83%	9.17%	-5.34%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	5.93%	15.57%	-9.64%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	4.78%	14.51%	-9.73%

MFGSX vs. FBLTX - Expense Ratio Comparison

MFGSX has a 0.76% expense ratio, which is higher than FBLTX's 0.03% expense ratio.

Dividends

MFGSX vs. FBLTX - Dividend Comparison

MFGSX's dividend yield for the trailing twelve months is around 3.32%, less than FBLTX's 3.99% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FBLTX Fidelity SAI Long-Term Treasury Bond Index Fund	3.99%	4.04%	3.60%	3.29%	2.25%	1.81%	6.73%	2.39%	2.87%	2.68%	3.70%	0.39%
MFGSX MFS Government Securities Fund	3.32%	3.47%	3.13%	2.51%	1.19%	1.03%	1.83%	2.11%	2.32%	2.43%	2.31%	2.16%

Frequently Asked Questions

Can I hold both MFGSX and FBLTX in my portfolio?

MFGSX and FBLTX have a correlation of 0.86, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, MFGSX or FBLTX?

FBLTX has higher volatility (2.54%) compared to MFGSX (0.97%). In terms of maximum drawdown, MFGSX dropped -19.50% vs FBLTX's -49.06%.

Which has better risk-adjusted returns?

MFGSX currently has the higher Sharpe Ratio (0.24 vs -0.27), 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.