VBIRX vs. FZOLX

Last updated Jun 5, 2026

VBIRX (Vanguard Short-Term Bond Index Fund Admiral Shares) and FZOLX (Fidelity SAI Low Duration Income Fund) are both mutual funds - VBIRX is a Total Bond Market fund managed by Vanguard, while FZOLX is a Ultrashort Bond fund managed by Fidelity. Over the past 5 years, VBIRX returned 1.59%/yr vs 3.53%/yr for FZOLX. At a 0.43 correlation, their price movements are largely independent. VBIRX charges 0.07%/yr vs 0.22%/yr for FZOLX.

Performance

VBIRX vs. FZOLX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Vanguard Short-Term Bond Index Fund Admiral Shares (VBIRX) and Fidelity SAI Low Duration Income Fund (FZOLX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, VBIRX achieves a 0.20% return, which is significantly lower than FZOLX's 1.36% return.

VBIRX

• 1D: -0.10%
• 1M: 0.05%
• YTD: 0.20%
• 6M: 0.54%
• 1Y: 3.43%
• 3Y*: 4.38%
• 5Y*: 1.59%
• 10Y*: 1.91%

FZOLX

• 1D: 0.00%
• 1M: 0.32%
• YTD: 1.36%
• 6M: 1.79%
• 1Y: 4.26%
• 3Y*: 5.14%
• 5Y*: 3.53%
• 10Y*: —

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

VBIRX vs. FZOLX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020
VBIRX Vanguard Short-Term Bond Index Fund Admiral Shares	0.20%	6.09%	3.75%	4.87%	-5.63%	-1.20%	0.31%
FZOLX Fidelity SAI Low Duration Income Fund	1.36%	4.85%	5.59%	5.72%	0.34%	-0.04%	0.11%

Correlation

The correlation between VBIRX and FZOLX is 0.51, which is moderate. They share some common price drivers but move independently often enough to provide real diversification benefit when combined.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.51
Correlation (3Y) Calculated over the trailing 3-year period	0.48
Correlation (5Y) Calculated over the trailing 5-year period	0.46
Correlation (All Time) Calculated using the full available price history since Sep 16, 2020	0.43

The correlation between VBIRX and FZOLX has been stable across timeframes, ranging from 0.43 to 0.51 - a consistent structural relationship.

Return for Risk

VBIRX vs. FZOLX — Risk / Return Rank

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

VBIRX

VBIRX Risk / Return Rank: 36
VBIRX Sharpe Ratio Rank: 31
VBIRX Sortino Ratio Rank: 42
VBIRX Omega Ratio Rank: 36
VBIRX Calmar Ratio Rank: 39
VBIRX Martin Ratio Rank: 34

FZOLX

FZOLX Risk / Return Rank: 98
FZOLX Sharpe Ratio Rank: 95
FZOLX Sortino Ratio Rank: 99
FZOLX Omega Ratio Rank: 99
FZOLX Calmar Ratio Rank: 99
FZOLX Martin Ratio Rank: 100

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.

VBIRX vs. FZOLX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Vanguard Short-Term Bond Index Fund Admiral Shares (VBIRX) and Fidelity SAI Low Duration Income Fund (FZOLX). 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.

	VBIRX	FZOLX	Difference
Sharpe ratio: Return per unit of total volatility	1.62	3.36	-1.74
Sortino ratio: Return per unit of downside risk	2.73	10.53	-7.80
Omega ratio: Gain probability vs. loss probability	1.32	3.63	-2.31
Calmar ratio: Return relative to maximum drawdown	2.36	14.30	-11.94
Martin ratio: Return relative to average drawdown	7.65	74.84	-67.18
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

VBIRX vs. FZOLX - Sharpe Ratio Comparison

The current VBIRX Sharpe Ratio is 1.62, which is lower than the FZOLX Sharpe Ratio of 3.36. The chart below compares the historical Sharpe Ratios of VBIRX and FZOLX, 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

	VBIRX	FZOLX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.62	3.36	-1.74
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.54	2.91	-2.37
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.80	—	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.97	2.72	-1.75

Drawdowns

VBIRX vs. FZOLX - Drawdown Comparison

The maximum VBIRX drawdown since its inception was -8.69%, which is greater than FZOLX's maximum drawdown of -1.10%. Use the drawdown chart below to compare losses from any high point for VBIRX and FZOLX.

Drawdown Indicators

	VBIRX	FZOLX	Difference
Max Drawdown Largest peak-to-trough decline	-8.69%	-1.10%	-7.59%
Max Drawdown (1Y) Largest decline over 1 year	-1.54%	-0.30%	-1.24%
Max Drawdown (3Y) Largest decline over 3 years	-1.55%	-0.30%	-1.25%
Max Drawdown (5Y) Largest decline over 5 years	-8.64%	-1.10%	-7.54%
Max Drawdown (10Y) Largest decline over 10 years	-8.69%	—	—
Current Drawdown Current decline from peak	-0.73%	0.00%	-0.73%
Average Drawdown Average peak-to-trough decline	-0.99%	-0.13%	-0.86%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.48%	0.06%	+0.42%

Volatility

VBIRX vs. FZOLX - Volatility Comparison

Vanguard Short-Term Bond Index Fund Admiral Shares (VBIRX) has a higher volatility of 0.69% compared to Fidelity SAI Low Duration Income Fund (FZOLX) at 0.38%. This indicates that VBIRX's price experiences larger fluctuations and is considered to be riskier than FZOLX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	VBIRX	FZOLX	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.69%	0.38%	+0.31%
Volatility (6M) Calculated over the trailing 6-month period	1.59%	0.88%	+0.71%
Volatility (1Y) Calculated over the trailing 1-year period	2.26%	1.27%	+0.99%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	2.96%	1.22%	+1.74%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	2.40%	1.15%	+1.25%

VBIRX vs. FZOLX - Expense Ratio Comparison

VBIRX has a 0.07% expense ratio, which is lower than FZOLX's 0.22% 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

VBIRX vs. FZOLX - Dividend Comparison

VBIRX's dividend yield for the trailing twelve months is around 4.00%, less than FZOLX's 5.09% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FZOLX Fidelity SAI Low Duration Income Fund	5.09%	5.26%	5.15%	4.03%	1.14%	0.16%	0.01%	0.00%	0.00%	0.00%	0.00%	0.00%
VBIRX Vanguard Short-Term Bond Index Fund Admiral Shares	4.00%	3.83%	3.37%	2.41%	1.46%	1.22%	1.77%	2.24%	2.03%	1.66%	1.50%	1.41%

Frequently Asked Questions

Can I hold both VBIRX and FZOLX in my portfolio?

VBIRX and FZOLX have a correlation of 0.51, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, VBIRX or FZOLX?

VBIRX has higher volatility (0.69%) compared to FZOLX (0.38%). In terms of maximum drawdown, VBIRX dropped -8.69% vs FZOLX's -1.10%.

Which has better risk-adjusted returns?

FZOLX currently has the higher Sharpe Ratio (3.36 vs 1.62), 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.