VMBIX vs. VUSFX

Last updated Jun 3, 2026

VMBIX (Vanguard Mortgage-Backed Securities Index Fund Institutional Shares) and VUSFX (Vanguard Ultra-Short-Term Bond Fund Admiral Shares) are both Total Bond Market funds from Vanguard. Over the past 10 years, VMBIX returned 1.40%/yr vs 2.71%/yr for VUSFX. At a 0.50 correlation, their price movements are largely independent. VMBIX charges 0.05%/yr vs 0.10%/yr for VUSFX.

Performance

VMBIX vs. VUSFX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Vanguard Mortgage-Backed Securities Index Fund Institutional Shares (VMBIX) and Vanguard Ultra-Short-Term Bond Fund Admiral Shares (VUSFX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, VMBIX achieves a 0.82% return, which is significantly lower than VUSFX's 1.42% return. Over the past 10 years, VMBIX has underperformed VUSFX with an annualized return of 1.40%, while VUSFX has yielded a comparatively higher 2.71% annualized return.

VMBIX

• 1D: -0.12%
• 1M: 0.03%
• YTD: 0.82%
• 6M: 1.13%
• 1Y: 6.96%
• 3Y*: 4.70%
• 5Y*: 0.54%
• 10Y*: 1.40%

VUSFX

• 1D: 0.00%
• 1M: 0.36%
• YTD: 1.42%
• 6M: 1.76%
• 1Y: 4.51%
• 3Y*: 5.44%
• 5Y*: 3.50%
• 10Y*: 2.71%

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

VMBIX vs. VUSFX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
VMBIX Vanguard Mortgage-Backed Securities Index Fund Institutional Shares	0.82%	8.44%	1.78%	4.97%	-11.56%	-1.30%	3.77%	6.19%	0.88%	2.38%
VUSFX Vanguard Ultra-Short-Term Bond Fund Admiral Shares	1.42%	5.11%	6.11%	5.53%	-0.38%	0.08%	2.10%	3.39%	2.10%	1.37%

Correlation

The correlation between VMBIX and VUSFX is 0.56, 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	0.56
Correlation (3Y) Calculated over the trailing 3-year period	0.61
Correlation (5Y) Calculated over the trailing 5-year period	0.64
Correlation (10Y) Calculated over the trailing 10-year period	0.50
Correlation (All Time) Calculated using the full available price history since Jan 5, 2016	0.50

The correlation between VMBIX and VUSFX shifts across timeframes, from 0.50 (all time) to 0.64 (5 years), reflecting how their relationship changes across market environments.

Return for Risk

VMBIX vs. VUSFX — Risk / Return Rank

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

VMBIX

VMBIX Risk / Return Rank: 41
VMBIX Sharpe Ratio Rank: 37
VMBIX Sortino Ratio Rank: 40
VMBIX Omega Ratio Rank: 37
VMBIX Calmar Ratio Rank: 48
VMBIX Martin Ratio Rank: 43

VUSFX

VUSFX Risk / Return Rank: 100
VUSFX Sharpe Ratio Rank: 100
VUSFX Sortino Ratio Rank: 100
VUSFX Omega Ratio Rank: 100
VUSFX Calmar Ratio Rank: 100
VUSFX 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.

VMBIX vs. VUSFX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Vanguard Mortgage-Backed Securities Index Fund Institutional Shares (VMBIX) and Vanguard Ultra-Short-Term Bond Fund Admiral Shares (VUSFX). 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.

	VMBIX	VUSFX	Difference
Sharpe ratio Return per unit of total volatility	1.76	7.69	-5.93
Sortino ratio Return per unit of downside risk	2.64	15.39	-12.75
Omega ratio Gain probability vs. loss probability	1.32	4.69	-3.37
Calmar ratio Return relative to maximum drawdown	2.64	18.20	-15.56
Martin ratio Return relative to average drawdown	9.10	108.57	-99.47
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

VMBIX vs. VUSFX - Sharpe Ratio Comparison

The current VMBIX Sharpe Ratio is 1.76, which is lower than the VUSFX Sharpe Ratio of 7.69. The chart below compares the historical Sharpe Ratios of VMBIX and VUSFX, 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

	VMBIX	VUSFX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.76	7.69	-5.93
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.09	4.35	-4.26
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.29	4.00	-3.71
Sharpe Ratio (All Time) Calculated using the full available price history	0.51	4.00	-3.49

Drawdowns

VMBIX vs. VUSFX - Drawdown Comparison

The maximum VMBIX drawdown since its inception was -17.44%, which is greater than VUSFX's maximum drawdown of -1.71%. Use the drawdown chart below to compare losses from any high point for VMBIX and VUSFX.

Drawdown Indicators

	VMBIX	VUSFX	Difference
Max Drawdown Largest peak-to-trough decline	-17.44%	-1.71%	-15.73%
Max Drawdown (1Y) Largest decline over 1 year	-2.63%	-0.25%	-2.38%
Max Drawdown (3Y) Largest decline over 3 years	-7.51%	-0.35%	-7.16%
Max Drawdown (5Y) Largest decline over 5 years	-17.11%	-1.71%	-15.40%
Max Drawdown (10Y) Largest decline over 10 years	-17.44%	-1.71%	-15.73%
Current Drawdown Current decline from peak	-1.19%	0.00%	-1.19%
Average Drawdown Average peak-to-trough decline	-2.51%	-0.15%	-2.36%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.76%	0.04%	+0.72%

Volatility

VMBIX vs. VUSFX - Volatility Comparison

Vanguard Mortgage-Backed Securities Index Fund Institutional Shares (VMBIX) has a higher volatility of 1.47% compared to Vanguard Ultra-Short-Term Bond Fund Admiral Shares (VUSFX) at 0.13%. This indicates that VMBIX's price experiences larger fluctuations and is considered to be riskier than VUSFX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	VMBIX	VUSFX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.47%	0.13%	+1.34%
Volatility (6M) Calculated over the trailing 6-month period	2.77%	0.41%	+2.36%
Volatility (1Y) Calculated over the trailing 1-year period	3.81%	0.59%	+3.22%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	6.37%	0.81%	+5.56%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	4.79%	0.68%	+4.11%

VMBIX vs. VUSFX - Expense Ratio Comparison

VMBIX has a 0.05% expense ratio, which is lower than VUSFX's 0.10% 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

VMBIX vs. VUSFX - Dividend Comparison

VMBIX's dividend yield for the trailing twelve months is around 4.18%, less than VUSFX's 4.53% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
VMBIX Vanguard Mortgage-Backed Securities Index Fund Institutional Shares	4.18%	4.20%	4.27%	3.29%	2.33%	1.01%	2.02%	2.76%	2.74%	2.18%	2.13%	2.04%
VUSFX Vanguard Ultra-Short-Term Bond Fund Admiral Shares	4.53%	4.73%	5.52%	4.15%	1.38%	0.53%	1.62%	2.68%	2.23%	1.52%	1.07%	0.00%

Frequently Asked Questions

Can I hold both VMBIX and VUSFX in my portfolio?

VMBIX and VUSFX have a correlation of 0.56, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, VMBIX or VUSFX?

VMBIX has higher volatility (1.47%) compared to VUSFX (0.13%). In terms of maximum drawdown, VMBIX dropped -17.44% vs VUSFX's -1.71%.

Which has better risk-adjusted returns?

VUSFX currently has the higher Sharpe Ratio (7.69 vs 1.76), 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.