FNDSX vs. FBLTX

Last updated Jun 4, 2026

FNDSX (Fidelity Sustainability Bond Index Fund) and FBLTX (Fidelity SAI Long-Term Treasury Bond Index Fund) are both mutual funds - FNDSX is a Total Bond Market fund managed by Fidelity, while FBLTX is a Government Bonds fund managed by Fidelity. Over the past 5 years, FNDSX returned 0.02%/yr vs -6.17%/yr for FBLTX. Their correlation of 0.89 suggests significant overlap in exposure. FNDSX charges 0.10%/yr vs 0.03%/yr for FBLTX.

Performance

FNDSX vs. FBLTX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Fidelity Sustainability Bond Index Fund (FNDSX) 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, FNDSX achieves a 0.42% return, which is significantly higher than FBLTX's -0.08% return.

FNDSX

• 1D: 0.00%
• 1M: 0.44%
• YTD: 0.42%
• 6M: 0.31%
• 1Y: 5.25%
• 3Y*: 3.92%
• 5Y*: 0.02%
• 10Y*: —

FBLTX

• 1D: 0.15%
• 1M: 1.13%
• YTD: -0.08%
• 6M: -1.63%
• 1Y: 5.28%
• 3Y*: -1.70%
• 5Y*: -6.17%
• 10Y*: -1.68%

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

FNDSX vs. FBLTX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018
FNDSX Fidelity Sustainability Bond Index Fund	0.42%	7.03%	1.23%	5.44%	-13.34%	-2.22%	6.95%	8.30%	1.89%
FBLTX Fidelity SAI Long-Term Treasury Bond Index Fund	-0.08%	4.39%	-8.05%	2.71%	-31.84%	-4.89%	18.27%	14.36%	2.16%

Correlation

The correlation between FNDSX and FBLTX is 0.89, 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	0.89
Correlation (3Y) Calculated over the trailing 3-year period	0.91
Correlation (5Y) Calculated over the trailing 5-year period	0.91
Correlation (All Time) Calculated using the full available price history since Jun 20, 2018	0.89

The correlation between FNDSX and FBLTX has been stable across timeframes, ranging from 0.89 to 0.91 - a consistent structural relationship.

Return for Risk

FNDSX vs. FBLTX — Risk / Return Rank

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

FNDSX

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

FBLTX

FBLTX Risk / Return Rank: 6
FBLTX Sharpe Ratio Rank: 7
FBLTX Sortino Ratio Rank: 6
FBLTX Omega Ratio Rank: 6
FBLTX Calmar Ratio Rank: 7
FBLTX Martin Ratio Rank: 6

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.

FNDSX vs. FBLTX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity Sustainability Bond Index Fund (FNDSX) 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.

	FNDSX	FBLTX	Difference
Sharpe ratio: Return per unit of total volatility	1.33	0.53	+0.80
Sortino ratio: Return per unit of downside risk	2.00	0.82	+1.18
Omega ratio: Gain probability vs. loss probability	1.24	1.09	+0.14
Calmar ratio: Return relative to maximum drawdown	1.79	0.67	+1.12
Martin ratio: Return relative to average drawdown	5.39	1.71	+3.68
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

FNDSX vs. FBLTX - Sharpe Ratio Comparison

The current FNDSX Sharpe Ratio is 1.33, which is higher than the FBLTX Sharpe Ratio of 0.53. The chart below compares the historical Sharpe Ratios of FNDSX 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.

Sharpe Ratios by Period

	FNDSX	FBLTX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.33	0.53	+0.80
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.00	-0.39	+0.40
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	—	-0.12	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.33	-0.05	+0.38

Drawdowns

FNDSX vs. FBLTX - Drawdown Comparison

The maximum FNDSX drawdown since its inception was -19.72%, smaller than the maximum FBLTX drawdown of -49.06%. Use the drawdown chart below to compare losses from any high point for FNDSX and FBLTX.

Drawdown Indicators

	FNDSX	FBLTX	Difference
Max Drawdown Largest peak-to-trough decline	-19.72%	-49.06%	+29.34%
Max Drawdown (1Y) Largest decline over 1 year	-2.94%	-7.66%	+4.72%
Max Drawdown (3Y) Largest decline over 3 years	-6.11%	-19.12%	+13.01%
Max Drawdown (5Y) Largest decline over 5 years	-18.30%	-44.19%	+25.89%
Max Drawdown (10Y) Largest decline over 10 years	—	-49.06%	—
Current Drawdown Current decline from peak	-3.74%	-41.01%	+37.27%
Average Drawdown Average peak-to-trough decline	-6.50%	-20.99%	+14.49%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.98%	3.01%	-2.03%

Volatility

FNDSX vs. FBLTX - Volatility Comparison

The current volatility for Fidelity Sustainability Bond Index Fund (FNDSX) is 1.31%, while Fidelity SAI Long-Term Treasury Bond Index Fund (FBLTX) has a volatility of 2.80%. This indicates that FNDSX 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

	FNDSX	FBLTX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.31%	2.80%	-1.49%
Volatility (6M) Calculated over the trailing 6-month period	2.81%	6.56%	-3.75%
Volatility (1Y) Calculated over the trailing 1-year period	3.98%	9.82%	-5.84%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	6.01%	15.70%	-9.69%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	5.31%	14.59%	-9.28%

FNDSX vs. FBLTX - Expense Ratio Comparison

FNDSX has a 0.10% expense ratio, which is higher than FBLTX's 0.03% expense ratio. However, both funds are considered low-cost compared to the broader market, where average expense ratios usually range from 0.3% to 0.9%.

Dividends

FNDSX vs. FBLTX - Dividend Comparison

FNDSX's dividend yield for the trailing twelve months is around 3.95%, less than FBLTX's 4.17% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FBLTX Fidelity SAI Long-Term Treasury Bond Index Fund	4.17%	4.04%	3.60%	3.29%	2.25%	1.81%	6.73%	2.39%	2.87%	2.68%	3.70%	0.39%
FNDSX Fidelity Sustainability Bond Index Fund	3.95%	3.84%	3.53%	2.84%	1.55%	1.17%	1.79%	3.17%	1.56%	0.00%	0.00%	0.00%

Frequently Asked Questions

Can I hold both FNDSX and FBLTX in my portfolio?

FNDSX and FBLTX have a correlation of 0.89, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, FNDSX or FBLTX?

FBLTX has higher volatility (2.80%) compared to FNDSX (1.31%). In terms of maximum drawdown, FNDSX dropped -19.72% vs FBLTX's -49.06%.

Which has better risk-adjusted returns?

FNDSX currently has the higher Sharpe Ratio (1.33 vs 0.53), 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.