FNBGX vs. FXAIX

Last updated Aug 5, 2026

FNBGX (Fidelity Long-Term Treasury Bond Index Fund) and FXAIX (Fidelity 500 Index Fund) are both mutual funds - FNBGX is a Government Bonds fund tracking the Bloomberg U.S. Long Treasury Bond Index, while FXAIX is a S&P 500 fund tracking the S&P 500 Index. Both are passively managed. Over the past 5 years, FNBGX returned -7.42%/yr vs 13.14%/yr for FXAIX. Their -0.08 correlation means they have often moved in opposite directions in the past. FNBGX charges 0.03%/yr vs 0.02%/yr for FXAIX.

Performance

FNBGX vs. FXAIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Fidelity Long-Term Treasury Bond Index Fund (FNBGX) 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, FNBGX achieves a -3.27% return, which is significantly lower than FXAIX's 11.76% return.

FNBGX

• 1D: 0.34%
• 1M: -3.50%
• 6M: -3.07%
• YTD: -3.27%
• 1Y: -1.90%
• 3Y*: -0.16%
• 5Y*: -7.42%
• 10Y*: —
• ALL TIME*: -1.41%

FXAIX

• 1D: 1.48%
• 1M: 1.63%
• 6M: 10.50%
• YTD: 11.76%
• 1Y: 21.49%
• 3Y*: 20.87%
• 5Y*: 13.14%
• 10Y*: 15.18%
• ALL TIME*: 14.04%

*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)
FNBGX Fidelity Long-Term Treasury Bond Index Fund	$0.00	$0.00	$0.00
FXAIX Fidelity 500 Index Fund	$0.00	$0.00	$0.00

FNBGX vs. FXAIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
FNBGX Fidelity Long-Term Treasury Bond Index Fund	-3.27%	5.30%	-6.18%	3.20%	-29.89%	-5.17%	17.58%	14.24%	-1.62%	1.86%
FXAIX Fidelity 500 Index Fund	11.76%	17.84%	25.01%	26.29%	-18.14%	28.71%	18.42%	31.48%	-4.43%	4.82%

Correlation

The correlation between FNBGX and FXAIX is 0.25, which is low. Their historical price movements had little consistent relationship.

	Correlation
Correlation (1Y) Focuses on recent behavior, but can change the most.	0.25
Correlation (3Y) Balances recent behavior with more history.	0.17
Correlation (5Y) Shows whether the relationship held over a longer period.	0.08
Correlation (All Time) Calculated using the full available price history since Oct 19, 2017	-0.08

The correlation between FNBGX and FXAIX shifts across timeframes, from -0.08 (all time) to 0.25 (1 year), reflecting how their relationship changes across market environments.

Return for Risk

FNBGX vs. FXAIX — Risk / Return Rank

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

FNBGX

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

FXAIX

FXAIX Risk / Return Rank: 75
FXAIX Sharpe Ratio Rank: 75
FXAIX Sortino Ratio Rank: 71
FXAIX Omega Ratio Rank: 70
FXAIX Calmar Ratio Rank: 77
FXAIX Martin Ratio Rank: 85

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.

FNBGX vs. FXAIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity Long-Term Treasury Bond Index Fund (FNBGX) 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.

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.

	FNBGX	FXAIX	Difference
Sharpe ratio: Return per unit of total volatility	-0.20	1.82	-2.03
Sortino ratio: Return per unit of downside risk	-0.22	2.51	-2.74
Omega ratio: Gain probability vs. loss probability	0.97	1.33	-0.35
Calmar ratio: Return relative to maximum drawdown	-0.23	2.63	-2.86
Martin ratio: Return relative to average drawdown	-0.51	11.30	-11.81

FNBGX vs. FXAIX - Sharpe Ratio Comparison

The current FNBGX Sharpe Ratio is -0.20, which is lower than the FXAIX Sharpe Ratio of 1.82. The chart below compares the historical Sharpe Ratios of FNBGX 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.

Drawdowns

FNBGX vs. FXAIX - Drawdown Comparison

The maximum FNBGX drawdown since its inception was -46.86%, which is greater than FXAIX's maximum drawdown of -33.79%. Use the drawdown chart below to compare losses from any high point for FNBGX and FXAIX.

Drawdown Indicators

	FNBGX	FXAIX	Difference
Max Drawdown Largest peak-to-trough decline	-46.86%	-33.79%	-13.07%
Max Drawdown (1Y) Largest decline over 1 year	-7.38%	-8.89%	+1.51%
Max Drawdown (3Y) Largest decline over 3 years	-13.48%	-18.76%	+5.28%
Max Drawdown (5Y) Largest decline over 5 years	-41.54%	-24.50%	-17.04%
Max Drawdown (10Y) Largest decline over 10 years	—	-33.79%	—
Current Drawdown Current decline from peak	-39.30%	0.00%	-39.30%
Average Drawdown Average peak-to-trough decline	-21.94%	-3.77%	-18.17%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.32%	2.07%	+1.25%

Volatility

FNBGX vs. FXAIX - Volatility Comparison

The current volatility for Fidelity Long-Term Treasury Bond Index Fund (FNBGX) is 2.31%, while Fidelity 500 Index Fund (FXAIX) has a volatility of 3.81%. This indicates that FNBGX 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

	FNBGX	FXAIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	2.31%	3.81%	-1.50%
Volatility (6M) Calculated over the trailing 6-month period	6.38%	10.20%	-3.82%
Volatility (1Y) Calculated over the trailing 1-year period	8.37%	12.86%	-4.49%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	14.46%	17.04%	-2.58%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	14.11%	18.09%	-3.98%

FNBGX vs. FXAIX - Expense Ratio Comparison

FNBGX 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

FNBGX vs. FXAIX - Dividend Comparison

FNBGX's dividend yield for the trailing twelve months is around 3.81%, more than FXAIX's 1.04% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FNBGX Fidelity Long-Term Treasury Bond Index Fund	3.81%	3.88%	3.75%	3.20%	2.26%	2.47%	3.96%	2.63%	2.93%	0.70%	0.00%	0.00%
FXAIX Fidelity 500 Index Fund	1.04%	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 FNBGX and FXAIX in my portfolio?

FNBGX and FXAIX have a correlation of 0.25, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, FNBGX or FXAIX?

FXAIX has higher volatility (3.81%) compared to FNBGX (2.31%). In terms of maximum drawdown, FNBGX dropped -46.86% vs FXAIX's -33.79%.

Which has better risk-adjusted returns?

FXAIX currently has the higher Sharpe Ratio (1.82 vs -0.20), 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.