VBIPX vs. VMBIX

Last updated Jun 24, 2026

VBIPX (Vanguard Short-Term Bond Index Fund Institutional Plus) and VMBIX (Vanguard Mortgage-Backed Securities Index Fund Institutional Shares) are both Total Bond Market funds from Vanguard. Over the past 10 years, VBIPX returned 1.83%/yr vs 1.37%/yr for VMBIX. A 0.75 correlation means they provide meaningful diversification when combined. VBIPX charges 0.04%/yr vs 0.05%/yr for VMBIX.

Performance

VBIPX vs. VMBIX - Performance Comparison

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

Returns By Period

In the year-to-date period, VBIPX achieves a -0.08% return, which is significantly lower than VMBIX's 0.82% return. Over the past 10 years, VBIPX has outperformed VMBIX with an annualized return of 1.83%, while VMBIX has yielded a comparatively lower 1.37% annualized return.

VBIPX

• 1D: -0.20%
• 1M: 0.15%
• YTD: -0.08%
• 6M: 0.36%
• 1Y: 3.06%
• 3Y*: 4.36%
• 5Y*: 1.51%
• 10Y*: 1.83%

VMBIX

• 1D: -0.24%
• 1M: 0.67%
• YTD: 0.82%
• 6M: 0.94%
• 1Y: 5.71%
• 3Y*: 4.55%
• 5Y*: 0.59%
• 10Y*: 1.37%

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

VBIPX vs. VMBIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
VBIPX Vanguard Short-Term Bond Index Fund Institutional Plus	-0.08%	6.12%	3.78%	4.45%	-5.68%	-1.17%	4.73%	4.89%	1.38%	1.21%
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%

Correlation

The correlation between VBIPX and VMBIX is 0.81, indicating a strong positive relationship between their price movements. Combining them offers limited diversification - they tend to fall together during downturns.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.81
Correlation (3Y) Calculated over the trailing 3-year period	0.81
Correlation (5Y) Calculated over the trailing 5-year period	0.83
Correlation (10Y) Calculated over the trailing 10-year period	0.77
Correlation (All Time) Calculated using the full available price history since Sep 27, 2011	0.75

The correlation between VBIPX and VMBIX has been stable across timeframes, ranging from 0.75 to 0.83 - a consistent structural relationship.

Return for Risk

VBIPX vs. VMBIX — Risk / Return Rank

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

VBIPX

VBIPX Risk / Return Rank: 31
VBIPX Sharpe Ratio Rank: 28
VBIPX Sortino Ratio Rank: 36
VBIPX Omega Ratio Rank: 31
VBIPX Calmar Ratio Rank: 33
VBIPX Martin Ratio Rank: 29

VMBIX

VMBIX Risk / Return Rank: 37
VMBIX Sharpe Ratio Rank: 35
VMBIX Sortino Ratio Rank: 37
VMBIX Omega Ratio Rank: 35
VMBIX Calmar Ratio Rank: 40
VMBIX Martin Ratio Rank: 35

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.

VBIPX vs. VMBIX - Risk-Adjusted Trends Comparison

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

Values are calculated on a 1-year rolling basis and updated daily. Risk-adjusted metrics are more stable over longer periods — use the period switch above to explore them.

	VBIPX	VMBIX	Difference
Sharpe ratio: Return per unit of total volatility	1.39	1.59	-0.20
Sortino ratio: Return per unit of downside risk	2.33	2.37	-0.05
Omega ratio: Gain probability vs. loss probability	1.27	1.29	-0.02
Calmar ratio: Return relative to maximum drawdown	2.06	2.28	-0.22
Martin ratio: Return relative to average drawdown	6.33	7.34	-1.01

VBIPX vs. VMBIX - Sharpe Ratio Comparison

The current VBIPX Sharpe Ratio is 1.39, which is comparable to the VMBIX Sharpe Ratio of 1.59. The chart below compares the historical Sharpe Ratios of VBIPX and VMBIX, calculated using daily returns over the previous 12 months. A higher Sharpe Ratio indicates better risk-adjusted performance relative to the risk-free rate.

Drawdowns

VBIPX vs. VMBIX - Drawdown Comparison

The maximum VBIPX drawdown since its inception was -8.72%, smaller than the maximum VMBIX drawdown of -17.44%. Use the drawdown chart below to compare losses from any high point for VBIPX and VMBIX.

Drawdown Indicators

	VBIPX	VMBIX	Difference
Max Drawdown Largest peak-to-trough decline	-8.72%	-17.44%	+8.72%
Max Drawdown (1Y) Largest decline over 1 year	-1.54%	-2.63%	+1.09%
Max Drawdown (3Y) Largest decline over 3 years	-1.54%	-7.51%	+5.97%
Max Drawdown (5Y) Largest decline over 5 years	-8.69%	-17.11%	+8.42%
Max Drawdown (10Y) Largest decline over 10 years	-8.72%	-17.44%	+8.72%
Current Drawdown Current decline from peak	-1.01%	-1.19%	+0.18%
Average Drawdown Average peak-to-trough decline	-1.19%	-2.51%	+1.32%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.50%	0.82%	-0.32%

Volatility

VBIPX vs. VMBIX - Volatility Comparison

The current volatility for Vanguard Short-Term Bond Index Fund Institutional Plus (VBIPX) is 0.72%, while Vanguard Mortgage-Backed Securities Index Fund Institutional Shares (VMBIX) has a volatility of 1.23%. This indicates that VBIPX experiences smaller price fluctuations and is considered to be less risky than VMBIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	VBIPX	VMBIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.72%	1.23%	-0.51%
Volatility (6M) Calculated over the trailing 6-month period	1.65%	2.88%	-1.23%
Volatility (1Y) Calculated over the trailing 1-year period	2.28%	3.77%	-1.49%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	2.97%	6.39%	-3.42%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	2.41%	4.81%	-2.40%

VBIPX vs. VMBIX - Expense Ratio Comparison

VBIPX has a 0.04% expense ratio, which is lower than VMBIX's 0.05% 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

VBIPX vs. VMBIX - Dividend Comparison

VBIPX's dividend yield for the trailing twelve months is around 4.04%, less than VMBIX's 4.18% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
VBIPX Vanguard Short-Term Bond Index Fund Institutional Plus	4.04%	3.86%	3.40%	2.01%	1.40%	1.26%	1.82%	2.27%	2.04%	1.69%	1.53%	1.46%
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%

Frequently Asked Questions

Can I hold both VBIPX and VMBIX in my portfolio?

VBIPX and VMBIX have a correlation of 0.81, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, VBIPX or VMBIX?

VMBIX has higher volatility (1.23%) compared to VBIPX (0.72%). In terms of maximum drawdown, VBIPX dropped -8.72% vs VMBIX's -17.44%.

Which has better risk-adjusted returns?

VMBIX currently has the higher Sharpe Ratio (1.59 vs 1.39), 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.