FZOLX vs. VBIRX

Last updated Jun 3, 2026

FZOLX (Fidelity SAI Low Duration Income Fund) and VBIRX (Vanguard Short-Term Bond Index Fund Admiral Shares) are both mutual funds - FZOLX is a Ultrashort Bond fund managed by Fidelity, while VBIRX is a Total Bond Market fund managed by Vanguard. Over the past 5 years, FZOLX returned 3.53%/yr vs 1.61%/yr for VBIRX. At a 0.43 correlation, their price movements are largely independent. FZOLX charges 0.22%/yr vs 0.07%/yr for VBIRX.

Performance

FZOLX vs. VBIRX - Performance Comparison

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

Returns By Period

In the year-to-date period, FZOLX achieves a 1.36% return, which is significantly higher than VBIRX's 0.30% return.

FZOLX

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

VBIRX

• 1D: -0.10%
• 1M: -0.05%
• YTD: 0.30%
• 6M: 0.64%
• 1Y: 3.74%
• 3Y*: 4.42%
• 5Y*: 1.61%
• 10Y*: 1.92%

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

FZOLX vs. VBIRX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020
FZOLX Fidelity SAI Low Duration Income Fund	1.36%	4.85%	5.59%	5.72%	0.34%	-0.04%	0.11%
VBIRX Vanguard Short-Term Bond Index Fund Admiral Shares	0.30%	6.09%	3.75%	4.87%	-5.63%	-1.20%	0.31%

Correlation

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

Return for Risk

FZOLX vs. VBIRX — Risk / Return Rank

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

FZOLX

FZOLX Risk / Return Rank: 99
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

VBIRX

VBIRX Risk / Return Rank: 39
VBIRX Sharpe Ratio Rank: 30
VBIRX Sortino Ratio Rank: 43
VBIRX Omega Ratio Rank: 36
VBIRX Calmar Ratio Rank: 47
VBIRX Martin Ratio Rank: 39

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.

FZOLX vs. VBIRX - Risk-Adjusted Trends Comparison

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

	FZOLX	VBIRX	Difference
Sharpe ratio Return per unit of total volatility	3.36	1.62	+1.74
Sortino ratio Return per unit of downside risk	10.53	2.73	+7.80
Omega ratio Gain probability vs. loss probability	3.63	1.32	+2.31
Calmar ratio Return relative to maximum drawdown	15.45	2.64	+12.81
Martin ratio Return relative to average drawdown	81.01	8.63	+72.38
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

FZOLX vs. VBIRX - Sharpe Ratio Comparison

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

	FZOLX	VBIRX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	3.36	1.62	+1.74
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	2.91	0.55	+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	2.72	0.97	+1.75

Drawdowns

FZOLX vs. VBIRX - Drawdown Comparison

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

Drawdown Indicators

	FZOLX	VBIRX	Difference
Max Drawdown Largest peak-to-trough decline	-1.10%	-8.69%	+7.59%
Max Drawdown (1Y) Largest decline over 1 year	-0.30%	-1.54%	+1.24%
Max Drawdown (3Y) Largest decline over 3 years	-0.30%	-1.55%	+1.25%
Max Drawdown (5Y) Largest decline over 5 years	-1.10%	-8.64%	+7.54%
Max Drawdown (10Y) Largest decline over 10 years	—	-8.69%	—
Current Drawdown Current decline from peak	0.00%	-0.63%	+0.63%
Average Drawdown Average peak-to-trough decline	-0.13%	-0.99%	+0.86%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.06%	0.47%	-0.41%

Volatility

FZOLX vs. VBIRX - Volatility Comparison

The current volatility for Fidelity SAI Low Duration Income Fund (FZOLX) is 0.38%, while Vanguard Short-Term Bond Index Fund Admiral Shares (VBIRX) has a volatility of 0.71%. This indicates that FZOLX experiences smaller price fluctuations and is considered to be less risky than VBIRX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	FZOLX	VBIRX	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.38%	0.71%	-0.33%
Volatility (6M) Calculated over the trailing 6-month period	0.94%	1.63%	-0.69%
Volatility (1Y) Calculated over the trailing 1-year period	1.28%	2.26%	-0.98%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	1.22%	2.96%	-1.74%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	1.15%	2.40%	-1.25%

FZOLX vs. VBIRX - Expense Ratio Comparison

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

FZOLX vs. VBIRX - Dividend Comparison

FZOLX's dividend yield for the trailing twelve months is around 5.09%, more than VBIRX's 3.99% 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	3.99%	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 FZOLX and VBIRX in my portfolio?

FZOLX and VBIRX 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, FZOLX or VBIRX?

VBIRX has higher volatility (0.71%) compared to FZOLX (0.38%). In terms of maximum drawdown, FZOLX dropped -1.10% vs VBIRX's -8.69%.

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.