VBIUX vs. VMBSX

Last updated Jun 25, 2026

VBIUX (Vanguard Intermediate-Term Bond Index Fund Institutional Plus) and VMBSX (Vanguard Mortgage-Backed Securities Index Fund Admiral Shares) are both Total Bond Market funds from Vanguard. Over the past 10 years, VBIUX returned 1.77%/yr vs 1.85%/yr for VMBSX. Their correlation of 0.84 suggests significant overlap in exposure. VBIUX charges 0.04%/yr vs 0.07%/yr for VMBSX.

Performance

VBIUX vs. VMBSX - Performance Comparison

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

Returns By Period

In the year-to-date period, VBIUX achieves a -0.42% return, which is significantly lower than VMBSX's 0.92% return. Both investments have delivered pretty close results over the past 10 years, with VBIUX having a 1.77% annualized return and VMBSX not far ahead at 1.85%.

VBIUX

• 1D: 0.10%
• 1M: 0.57%
• YTD: -0.42%
• 6M: -0.16%
• 1Y: 3.58%
• 3Y*: 4.29%
• 5Y*: 0.10%
• 10Y*: 1.77%

VMBSX

• 1D: 0.11%
• 1M: 0.78%
• YTD: 0.92%
• 6M: 0.87%
• 1Y: 5.47%
• 3Y*: 4.58%
• 5Y*: 0.61%
• 10Y*: 1.85%

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

VBIUX vs. VMBSX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
VBIUX Vanguard Intermediate-Term Bond Index Fund Institutional Plus	-0.42%	8.60%	1.56%	5.53%	-13.24%	-2.64%	9.83%	10.23%	-0.13%	3.90%
VMBSX Vanguard Mortgage-Backed Securities Index Fund Admiral Shares	0.92%	8.43%	1.76%	4.99%	-11.56%	-1.35%	3.74%	11.47%	0.87%	2.32%

Correlation

The correlation between VBIUX and VMBSX is 0.91, 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	0.91
Correlation (3Y) Calculated over the trailing 3-year period	0.93
Correlation (5Y) Calculated over the trailing 5-year period	0.92
Correlation (10Y) Calculated over the trailing 10-year period	0.86
Correlation (All Time) Calculated using the full available price history since Sep 27, 2011	0.84

The correlation between VBIUX and VMBSX has been stable across timeframes, ranging from 0.84 to 0.93 - a consistent structural relationship.

Return for Risk

VBIUX vs. VMBSX — Risk / Return Rank

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

VBIUX

VBIUX Risk / Return Rank: 14
VBIUX Sharpe Ratio Rank: 15
VBIUX Sortino Ratio Rank: 15
VBIUX Omega Ratio Rank: 13
VBIUX Calmar Ratio Rank: 14
VBIUX Martin Ratio Rank: 13

VMBSX

VMBSX Risk / Return Rank: 37
VMBSX Sharpe Ratio Rank: 36
VMBSX Sortino Ratio Rank: 38
VMBSX Omega Ratio Rank: 36
VMBSX Calmar Ratio Rank: 40
VMBSX Martin Ratio Rank: 34

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.

VBIUX vs. VMBSX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Vanguard Intermediate-Term Bond Index Fund Institutional Plus (VBIUX) and Vanguard Mortgage-Backed Securities Index Fund Admiral Shares (VMBSX). 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.

	VBIUX	VMBSX	Difference
Sharpe ratio: Return per unit of total volatility	0.95	1.57	-0.61
Sortino ratio: Return per unit of downside risk	1.43	2.32	-0.89
Omega ratio: Gain probability vs. loss probability	1.16	1.29	-0.12
Calmar ratio: Return relative to maximum drawdown	1.17	2.21	-1.04
Martin ratio: Return relative to average drawdown	3.16	6.99	-3.83

VBIUX vs. VMBSX - Sharpe Ratio Comparison

The current VBIUX Sharpe Ratio is 0.95, which is lower than the VMBSX Sharpe Ratio of 1.57. The chart below compares the historical Sharpe Ratios of VBIUX and VMBSX, 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

VBIUX vs. VMBSX - Drawdown Comparison

The maximum VBIUX drawdown since its inception was -19.18%, which is greater than VMBSX's maximum drawdown of -17.44%. Use the drawdown chart below to compare losses from any high point for VBIUX and VMBSX.

Drawdown Indicators

	VBIUX	VMBSX	Difference
Max Drawdown Largest peak-to-trough decline	-19.18%	-17.44%	-1.74%
Max Drawdown (1Y) Largest decline over 1 year	-3.33%	-2.67%	-0.66%
Max Drawdown (3Y) Largest decline over 3 years	-6.05%	-7.53%	+1.48%
Max Drawdown (5Y) Largest decline over 5 years	-18.83%	-17.12%	-1.71%
Max Drawdown (10Y) Largest decline over 10 years	-19.18%	-17.44%	-1.74%
Current Drawdown Current decline from peak	-2.21%	-1.11%	-1.10%
Average Drawdown Average peak-to-trough decline	-4.08%	-2.48%	-1.60%
Ulcer Index Depth and duration of drawdowns from previous peaks	1.23%	0.84%	+0.39%

Volatility

VBIUX vs. VMBSX - Volatility Comparison

Vanguard Intermediate-Term Bond Index Fund Institutional Plus (VBIUX) has a higher volatility of 1.29% compared to Vanguard Mortgage-Backed Securities Index Fund Admiral Shares (VMBSX) at 1.21%. This indicates that VBIUX's price experiences larger fluctuations and is considered to be riskier than VMBSX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	VBIUX	VMBSX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.29%	1.21%	+0.08%
Volatility (6M) Calculated over the trailing 6-month period	3.08%	2.85%	+0.23%
Volatility (1Y) Calculated over the trailing 1-year period	4.11%	3.77%	+0.34%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	6.39%	6.41%	-0.02%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	5.38%	4.87%	+0.51%

VBIUX vs. VMBSX - Expense Ratio Comparison

VBIUX has a 0.04% expense ratio, which is lower than VMBSX's 0.07% 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

VBIUX vs. VMBSX - Dividend Comparison

VBIUX's dividend yield for the trailing twelve months is around 4.26%, more than VMBSX's 4.16% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
VBIUX Vanguard Intermediate-Term Bond Index Fund Institutional Plus	4.26%	4.04%	3.82%	2.59%	2.42%	3.08%	2.95%	2.76%	2.89%	2.77%	3.09%	3.14%
VMBSX Vanguard Mortgage-Backed Securities Index Fund Admiral Shares	4.16%	4.18%	4.24%	3.28%	2.31%	0.99%	2.00%	7.48%	2.72%	2.16%	1.98%	2.01%

Frequently Asked Questions

Can I hold both VBIUX and VMBSX in my portfolio?

With a correlation of 0.91, VBIUX and VMBSX move almost identically. Holding both adds very little diversification - you're essentially doubling your position in the same market segment. Choosing one is usually more capital-efficient.

Which is riskier, VBIUX or VMBSX?

VBIUX has higher volatility (1.29%) compared to VMBSX (1.21%). In terms of maximum drawdown, VBIUX dropped -19.18% vs VMBSX's -17.44%.

Which has better risk-adjusted returns?

VMBSX currently has the higher Sharpe Ratio (1.57 vs 0.95), 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.