FBLTX vs. FXAIX

Last updated Jun 6, 2026

FBLTX (Fidelity SAI Long-Term Treasury Bond Index Fund) and FXAIX (Fidelity 500 Index Fund) are both mutual funds - FBLTX is a Government Bonds fund managed by Fidelity, while FXAIX is a S&P 500 fund tracking the S&P 500 Index. Over the past 10 years, FBLTX returned -1.61%/yr vs 15.57%/yr for FXAIX. At a correlation of -0.11, they often move in opposite directions. FBLTX charges 0.03%/yr vs 0.02%/yr for FXAIX.

Performance

FBLTX vs. FXAIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Fidelity SAI Long-Term Treasury Bond Index Fund (FBLTX) and Fidelity 500 Index Fund (FXAIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, FBLTX achieves a -0.23% return, which is significantly lower than FXAIX's 11.36% return. Over the past 10 years, FBLTX has underperformed FXAIX with an annualized return of -1.61%, while FXAIX has yielded a comparatively higher 15.57% annualized return.

FBLTX

• 1D: 0.15%
• 1M: -0.24%
• YTD: -0.23%
• 6M: -0.77%
• 1Y: 3.38%
• 3Y*: -1.66%
• 5Y*: -6.44%
• 10Y*: -1.61%

FXAIX

• 1D: 0.42%
• 1M: 3.11%
• YTD: 11.36%
• 6M: 11.04%
• 1Y: 29.24%
• 3Y*: 22.71%
• 5Y*: 14.00%
• 10Y*: 15.57%

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

FBLTX vs. FXAIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
FBLTX Fidelity SAI Long-Term Treasury Bond Index Fund	-0.23%	4.39%	-8.05%	2.71%	-31.84%	-4.89%	18.27%	14.36%	-1.24%	9.06%
FXAIX Fidelity 500 Index Fund	11.36%	17.84%	25.01%	26.29%	-18.14%	28.71%	18.42%	31.48%	-4.43%	21.82%

Correlation

The correlation between FBLTX and FXAIX is 0.20, which is low. Their price movements are largely independent, making them effective diversification partners.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.20
Correlation (3Y) Calculated over the trailing 3-year period	0.18
Correlation (5Y) Calculated over the trailing 5-year period	0.07
Correlation (10Y) Calculated over the trailing 10-year period	-0.09
Correlation (All Time) Calculated using the full available price history since Oct 19, 2015	-0.11

The correlation between FBLTX and FXAIX shifts across timeframes, from -0.11 (all time) to 0.20 (1 year), reflecting how their relationship changes across market environments.

Return for Risk

FBLTX vs. FXAIX — Risk / Return Rank

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

FBLTX

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

FXAIX

FXAIX Risk / Return Rank: 73
FXAIX Sharpe Ratio Rank: 73
FXAIX Sortino Ratio Rank: 66
FXAIX Omega Ratio Rank: 67
FXAIX Calmar Ratio Rank: 74
FXAIX Martin Ratio Rank: 84

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.

FBLTX vs. FXAIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity SAI Long-Term Treasury Bond Index Fund (FBLTX) and Fidelity 500 Index Fund (FXAIX). 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.

	FBLTX	FXAIX	Difference
Sharpe ratio: Return per unit of total volatility	0.37	2.42	-2.05
Sortino ratio: Return per unit of downside risk	0.59	3.29	-2.70
Omega ratio: Gain probability vs. loss probability	1.07	1.44	-0.37
Calmar ratio: Return relative to maximum drawdown	0.47	3.23	-2.76
Martin ratio: Return relative to average drawdown	1.17	15.07	-13.90
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

FBLTX vs. FXAIX - Sharpe Ratio Comparison

The current FBLTX Sharpe Ratio is 0.37, which is lower than the FXAIX Sharpe Ratio of 2.42. The chart below compares the historical Sharpe Ratios of FBLTX and FXAIX, 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

	FBLTX	FXAIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	0.37	2.42	-2.05
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	-0.41	0.83	-1.24
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	-0.11	0.86	-0.98
Sharpe Ratio (All Time) Calculated using the full available price history	-0.05	0.82	-0.88

Drawdowns

FBLTX vs. FXAIX - Drawdown Comparison

The maximum FBLTX drawdown since its inception was -49.06%, which is greater than FXAIX's maximum drawdown of -33.79%. Use the drawdown chart below to compare losses from any high point for FBLTX and FXAIX.

Drawdown Indicators

	FBLTX	FXAIX	Difference
Max Drawdown Largest peak-to-trough decline	-49.06%	-33.79%	-15.27%
Max Drawdown (1Y) Largest decline over 1 year	-7.66%	-8.89%	+1.23%
Max Drawdown (3Y) Largest decline over 3 years	-19.12%	-18.76%	-0.36%
Max Drawdown (5Y) Largest decline over 5 years	-44.19%	-24.50%	-19.69%
Max Drawdown (10Y) Largest decline over 10 years	-49.06%	-33.79%	-15.27%
Current Drawdown Current decline from peak	-41.10%	-0.31%	-40.79%
Average Drawdown Average peak-to-trough decline	-21.00%	-3.79%	-17.21%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.04%	1.90%	+1.14%

Volatility

FBLTX vs. FXAIX - Volatility Comparison

The current volatility for Fidelity SAI Long-Term Treasury Bond Index Fund (FBLTX) is 2.68%, while Fidelity 500 Index Fund (FXAIX) has a volatility of 2.87%. This indicates that FBLTX experiences smaller price fluctuations and is considered to be less risky than FXAIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	FBLTX	FXAIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	2.68%	2.87%	-0.19%
Volatility (6M) Calculated over the trailing 6-month period	6.44%	9.00%	-2.56%
Volatility (1Y) Calculated over the trailing 1-year period	9.78%	11.88%	-2.10%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	15.69%	16.91%	-1.22%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	14.58%	18.07%	-3.49%

FBLTX vs. FXAIX - Expense Ratio Comparison

FBLTX has a 0.03% expense ratio, which is higher than FXAIX's 0.02% 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

FBLTX vs. FXAIX - Dividend Comparison

FBLTX's dividend yield for the trailing twelve months is around 4.17%, more than FXAIX's 1.03% 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%
FXAIX Fidelity 500 Index Fund	1.03%	1.11%	1.25%	1.45%	1.69%	1.22%	1.60%	2.06%	2.72%	1.97%	2.52%	2.83%

Frequently Asked Questions

Can I hold both FBLTX and FXAIX in my portfolio?

FBLTX and FXAIX have a correlation of 0.20, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, FBLTX or FXAIX?

FXAIX has higher volatility (2.87%) compared to FBLTX (2.68%). In terms of maximum drawdown, FBLTX dropped -49.06% vs FXAIX's -33.79%.

Which has better risk-adjusted returns?

FXAIX currently has the higher Sharpe Ratio (2.42 vs 0.37), 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.