VBISX vs. FMFIX

Last updated Jun 4, 2026

VBISX (Vanguard Short-Term Bond Index Fund) and FMFIX (RBB Free Market Fixed Income Fund) are both Short-Term Bond funds. Over the past 10 years, VBISX returned 1.79%/yr vs 1.27%/yr for FMFIX. A 0.74 correlation means they provide meaningful diversification when combined. VBISX charges 0.15%/yr vs 0.68%/yr for FMFIX.

Performance

VBISX vs. FMFIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Vanguard Short-Term Bond Index Fund (VBISX) and RBB Free Market Fixed Income Fund (FMFIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, VBISX achieves a 0.26% return, which is significantly lower than FMFIX's 1.00% return. Over the past 10 years, VBISX has outperformed FMFIX with an annualized return of 1.79%, while FMFIX has yielded a comparatively lower 1.27% annualized return.

VBISX

• 1D: 0.00%
• 1M: 0.14%
• YTD: 0.26%
• 6M: 0.50%
• 1Y: 3.64%
• 3Y*: 4.14%
• 5Y*: 1.44%
• 10Y*: 1.79%

FMFIX

• 1D: 0.00%
• 1M: 0.40%
• YTD: 1.00%
• 6M: 1.05%
• 1Y: 3.70%
• 3Y*: 3.32%
• 5Y*: 0.95%
• 10Y*: 1.27%

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

VBISX vs. FMFIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
VBISX Vanguard Short-Term Bond Index Fund	0.26%	5.67%	3.66%	4.54%	-5.61%	-1.35%	4.63%	4.78%	1.27%	1.10%
FMFIX RBB Free Market Fixed Income Fund	1.00%	4.88%	0.71%	5.43%	-6.52%	-1.06%	3.28%	4.78%	0.65%	1.05%

Correlation

The correlation between VBISX and FMFIX is 0.70, 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	0.70
Correlation (3Y) Calculated over the trailing 3-year period	0.76
Correlation (5Y) Calculated over the trailing 5-year period	0.80
Correlation (10Y) Calculated over the trailing 10-year period	0.74
Correlation (All Time) Calculated using the full available price history since Jan 2, 2008	0.74

The correlation between VBISX and FMFIX has been stable across timeframes, ranging from 0.70 to 0.80 - a consistent structural relationship.

Return for Risk

VBISX vs. FMFIX — Risk / Return Rank

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

VBISX

VBISX Risk / Return Rank: 37
VBISX Sharpe Ratio Rank: 33
VBISX Sortino Ratio Rank: 43
VBISX Omega Ratio Rank: 39
VBISX Calmar Ratio Rank: 40
VBISX Martin Ratio Rank: 33

FMFIX

FMFIX Risk / Return Rank: 70
FMFIX Sharpe Ratio Rank: 62
FMFIX Sortino Ratio Rank: 72
FMFIX Omega Ratio Rank: 75
FMFIX Calmar Ratio Rank: 75
FMFIX Martin Ratio Rank: 64

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.

VBISX vs. FMFIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Vanguard Short-Term Bond Index Fund (VBISX) and RBB Free Market Fixed Income Fund (FMFIX). 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.

	VBISX	FMFIX	Difference
Sharpe ratio: Return per unit of total volatility	1.64	2.32	-0.68
Sortino ratio: Return per unit of downside risk	2.75	3.54	-0.79
Omega ratio: Gain probability vs. loss probability	1.33	1.49	-0.16
Calmar ratio: Return relative to maximum drawdown	2.37	3.41	-1.04
Martin ratio: Return relative to average drawdown	7.61	12.61	-5.00
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

VBISX vs. FMFIX - Sharpe Ratio Comparison

The current VBISX Sharpe Ratio is 1.64, which is comparable to the FMFIX Sharpe Ratio of 2.32. The chart below compares the historical Sharpe Ratios of VBISX and FMFIX, 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

	VBISX	FMFIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.64	2.32	-0.68
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.49	0.33	+0.16
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.75	0.53	+0.23
Sharpe Ratio (All Time) Calculated using the full available price history	1.34	0.62	+0.72

Drawdowns

VBISX vs. FMFIX - Drawdown Comparison

The maximum VBISX drawdown since its inception was -8.79%, smaller than the maximum FMFIX drawdown of -9.35%. Use the drawdown chart below to compare losses from any high point for VBISX and FMFIX.

Drawdown Indicators

	VBISX	FMFIX	Difference
Max Drawdown Largest peak-to-trough decline	-8.79%	-9.35%	+0.56%
Max Drawdown (1Y) Largest decline over 1 year	-1.54%	-1.09%	-0.45%
Max Drawdown (3Y) Largest decline over 3 years	-1.55%	-3.72%	+2.17%
Max Drawdown (5Y) Largest decline over 5 years	-8.72%	-9.26%	+0.54%
Max Drawdown (10Y) Largest decline over 10 years	-8.79%	-9.35%	+0.56%
Current Drawdown Current decline from peak	-0.66%	-0.10%	-0.56%
Average Drawdown Average peak-to-trough decline	-0.87%	-1.22%	+0.35%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.48%	0.29%	+0.19%

Volatility

VBISX vs. FMFIX - Volatility Comparison

Vanguard Short-Term Bond Index Fund (VBISX) has a higher volatility of 0.69% compared to RBB Free Market Fixed Income Fund (FMFIX) at 0.60%. This indicates that VBISX's price experiences larger fluctuations and is considered to be riskier than FMFIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	VBISX	FMFIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.69%	0.60%	+0.09%
Volatility (6M) Calculated over the trailing 6-month period	1.59%	1.23%	+0.36%
Volatility (1Y) Calculated over the trailing 1-year period	2.24%	1.61%	+0.63%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	2.94%	2.88%	+0.06%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	2.38%	2.43%	-0.05%

VBISX vs. FMFIX - Expense Ratio Comparison

VBISX has a 0.15% expense ratio, which is lower than FMFIX's 0.68% expense ratio.

Dividends

VBISX vs. FMFIX - Dividend Comparison

VBISX's dividend yield for the trailing twelve months is around 3.90%, more than FMFIX's 3.64% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FMFIX RBB Free Market Fixed Income Fund	3.64%	3.49%	0.71%	2.75%	1.35%	0.37%	1.22%	1.44%	2.45%	1.25%	0.58%	0.39%
VBISX Vanguard Short-Term Bond Index Fund	3.90%	3.44%	3.29%	2.10%	1.38%	1.16%	1.72%	2.16%	1.92%	1.58%	1.42%	1.34%

Frequently Asked Questions

Can I hold both VBISX and FMFIX in my portfolio?

VBISX and FMFIX have a correlation of 0.70, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, VBISX or FMFIX?

VBISX has higher volatility (0.69%) compared to FMFIX (0.60%). In terms of maximum drawdown, VBISX dropped -8.79% vs FMFIX's -9.35%.

Which has better risk-adjusted returns?

FMFIX currently has the higher Sharpe Ratio (2.32 vs 1.64), 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.