FIBUX vs. VBTIX

Last updated Jun 4, 2026

FIBUX (Fidelity Flex U.S. Bond Index Fund) and VBTIX (Vanguard Total Bond Market Index Fund Institutional Shares) are both Total Bond Market funds. Over the past 5 years, FIBUX returned 0.09%/yr vs 0.22%/yr for VBTIX. With a 0.97 correlation, they move nearly in lockstep. FIBUX charges 0.00%/yr vs 0.04%/yr for VBTIX.

Performance

FIBUX vs. VBTIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Fidelity Flex U.S. Bond Index Fund (FIBUX) and Vanguard Total Bond Market Index Fund Institutional Shares (VBTIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, FIBUX achieves a 0.46% return, which is significantly higher than VBTIX's 0.43% return.

FIBUX

• 1D: 0.00%
• 1M: 0.46%
• YTD: 0.46%
• 6M: 0.33%
• 1Y: 5.40%
• 3Y*: 4.04%
• 5Y*: 0.09%
• 10Y*: —

VBTIX

• 1D: 0.00%
• 1M: 0.55%
• YTD: 0.43%
• 6M: 0.35%
• 1Y: 5.36%
• 3Y*: 4.06%
• 5Y*: 0.22%
• 10Y*: 1.58%

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

FIBUX vs. VBTIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
FIBUX Fidelity Flex U.S. Bond Index Fund	0.46%	7.20%	1.31%	5.46%	-13.41%	-2.16%	7.08%	8.58%	0.12%	3.81%
VBTIX Vanguard Total Bond Market Index Fund Institutional Shares	0.43%	7.18%	1.27%	5.75%	-13.15%	-1.95%	7.75%	8.74%	-0.24%	4.02%

Correlation

The correlation between FIBUX and VBTIX is 0.96 - these two move nearly in lockstep. At this level, holding both provides almost no diversification benefit. If you already own one, adding the other does little to reduce portfolio risk.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.96
Correlation (3Y) Calculated over the trailing 3-year period	0.97
Correlation (5Y) Calculated over the trailing 5-year period	0.98
Correlation (All Time) Calculated using the full available price history since Mar 10, 2017	0.97

The correlation between FIBUX and VBTIX has been stable across timeframes, ranging from 0.96 to 0.98 - a consistent structural relationship.

Return for Risk

FIBUX vs. VBTIX — Risk / Return Rank

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

FIBUX

FIBUX Risk / Return Rank: 23
FIBUX Sharpe Ratio Rank: 23
FIBUX Sortino Ratio Rank: 24
FIBUX Omega Ratio Rank: 22
FIBUX Calmar Ratio Rank: 24
FIBUX Martin Ratio Rank: 21

VBTIX

VBTIX Risk / Return Rank: 23
VBTIX Sharpe Ratio Rank: 23
VBTIX Sortino Ratio Rank: 24
VBTIX Omega Ratio Rank: 22
VBTIX Calmar Ratio Rank: 25
VBTIX Martin Ratio Rank: 21

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.

FIBUX vs. VBTIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity Flex U.S. Bond Index Fund (FIBUX) and Vanguard Total Bond Market Index Fund Institutional Shares (VBTIX). 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.

	FIBUX	VBTIX	Difference
Sharpe ratio: Return per unit of total volatility	1.36	1.36	0.00
Sortino ratio: Return per unit of downside risk	2.03	2.05	-0.02
Omega ratio: Gain probability vs. loss probability	1.24	1.24	0.00
Calmar ratio: Return relative to maximum drawdown	1.83	1.86	-0.03
Martin ratio: Return relative to average drawdown	5.45	5.60	-0.15
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

FIBUX vs. VBTIX - Sharpe Ratio Comparison

The current FIBUX Sharpe Ratio is 1.36, which is comparable to the VBTIX Sharpe Ratio of 1.36. The chart below compares the historical Sharpe Ratios of FIBUX and VBTIX, 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

	FIBUX	VBTIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.36	1.36	0.00
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.02	0.04	-0.02
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	—	0.32	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.35	0.95	-0.59

Drawdowns

FIBUX vs. VBTIX - Drawdown Comparison

The maximum FIBUX drawdown since its inception was -19.76%, roughly equal to the maximum VBTIX drawdown of -18.90%. Use the drawdown chart below to compare losses from any high point for FIBUX and VBTIX.

Drawdown Indicators

	FIBUX	VBTIX	Difference
Max Drawdown Largest peak-to-trough decline	-19.76%	-18.90%	-0.86%
Max Drawdown (1Y) Largest decline over 1 year	-2.97%	-2.89%	-0.08%
Max Drawdown (3Y) Largest decline over 3 years	-6.09%	-5.99%	-0.10%
Max Drawdown (5Y) Largest decline over 5 years	-18.40%	-18.13%	-0.27%
Max Drawdown (10Y) Largest decline over 10 years	—	-18.90%	—
Current Drawdown Current decline from peak	-3.43%	-2.25%	-1.18%
Average Drawdown Average peak-to-trough decline	-5.79%	-2.32%	-3.47%
Ulcer Index Depth and duration of drawdowns from previous peaks	1.00%	0.96%	+0.04%

Volatility

FIBUX vs. VBTIX - Volatility Comparison

Fidelity Flex U.S. Bond Index Fund (FIBUX) and Vanguard Total Bond Market Index Fund Institutional Shares (VBTIX) have volatilities of 1.38% and 1.38%, respectively, indicating that both stocks experience similar levels of price fluctuations. This suggests that the risk associated with both stocks, as measured by volatility, is nearly the same. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	FIBUX	VBTIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.38%	1.38%	0.00%
Volatility (6M) Calculated over the trailing 6-month period	2.86%	2.80%	+0.06%
Volatility (1Y) Calculated over the trailing 1-year period	4.02%	3.97%	+0.05%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	6.04%	6.02%	+0.02%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	5.11%	4.98%	+0.13%

FIBUX vs. VBTIX - Expense Ratio Comparison

FIBUX has a 0.00% expense ratio, which is lower than VBTIX's 0.04% expense ratio. Despite the difference, both funds are considered low-cost compared to the broader market, where average expense ratios usually range from 0.3% to 0.9%.

Dividends

FIBUX vs. VBTIX - Dividend Comparison

FIBUX's dividend yield for the trailing twelve months is around 4.08%, more than VBTIX's 3.99% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FIBUX Fidelity Flex U.S. Bond Index Fund	4.08%	3.95%	3.65%	2.93%	1.62%	1.18%	2.32%	2.96%	2.70%	2.45%	0.00%	0.00%
VBTIX Vanguard Total Bond Market Index Fund Institutional Shares	3.99%	3.88%	3.69%	3.12%	2.61%	1.81%	2.41%	2.75%	2.58%	2.56%	2.54%	2.84%

Frequently Asked Questions

Can I hold both FIBUX and VBTIX in my portfolio?

With a correlation of 0.96, FIBUX and VBTIX move almost identically. Holding both adds very little diversification - you're essentially doubling your position in the same market segment. Choosing one is usually more capital-efficient.

Which is riskier, FIBUX or VBTIX?

VBTIX has higher volatility (1.38%) compared to FIBUX (1.38%). In terms of maximum drawdown, FIBUX dropped -19.76% vs VBTIX's -18.90%.

Which has better risk-adjusted returns?

VBTIX currently has the higher Sharpe Ratio (1.36 vs 1.36), 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.