VMBSX vs. VBLLX

Last updated Jun 21, 2026

VMBSX (Vanguard Mortgage-Backed Securities Index Fund Admiral Shares) and VBLLX (Vanguard Long-Term Bond Index Fund Institutional Shares) are both Total Bond Market funds from Vanguard. Over the past 10 years, VMBSX returned 1.89%/yr vs 0.89%/yr for VBLLX. A 0.75 correlation means they provide meaningful diversification when combined. VMBSX charges 0.07%/yr vs 0.05%/yr for VBLLX.

Performance

VMBSX vs. VBLLX - Performance Comparison

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

Returns By Period

In the year-to-date period, VMBSX achieves a 1.03% return, which is significantly higher than VBLLX's 0.94% return. Over the past 10 years, VMBSX has outperformed VBLLX with an annualized return of 1.89%, while VBLLX has yielded a comparatively lower 0.89% annualized return.

VMBSX

• 1D: 0.27%
• 1M: 0.94%
• YTD: 1.03%
• 6M: 1.14%
• 1Y: 6.22%
• 3Y*: 4.67%
• 5Y*: 0.64%
• 10Y*: 1.89%

VBLLX

• 1D: 0.38%
• 1M: 2.77%
• YTD: 0.94%
• 6M: 1.35%
• 1Y: 6.15%
• 3Y*: 1.96%
• 5Y*: -3.96%
• 10Y*: 0.89%

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

VMBSX vs. VBLLX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
VMBSX Vanguard Mortgage-Backed Securities Index Fund Admiral Shares	1.03%	8.43%	1.76%	4.99%	-11.56%	-1.35%	3.74%	11.47%	0.87%	2.32%
VBLLX Vanguard Long-Term Bond Index Fund Institutional Shares	0.94%	6.60%	-4.12%	7.13%	-27.20%	-3.08%	16.27%	19.15%	-4.71%	10.89%

Correlation

The correlation between VMBSX and VBLLX is 0.88, 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	0.88
Correlation (3Y) Calculated over the trailing 3-year period	0.90
Correlation (5Y) Calculated over the trailing 5-year period	0.86
Correlation (10Y) Calculated over the trailing 10-year period	0.78
Correlation (All Time) Calculated using the full available price history since Nov 23, 2009	0.75

The correlation between VMBSX and VBLLX shifts across timeframes, from 0.75 (all time) to 0.90 (3 years), reflecting how their relationship changes across market environments.

Return for Risk

VMBSX vs. VBLLX — Risk / Return Rank

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

VMBSX

VMBSX Risk / Return Rank: 41
VMBSX Sharpe Ratio Rank: 41
VMBSX Sortino Ratio Rank: 43
VMBSX Omega Ratio Rank: 40
VMBSX Calmar Ratio Rank: 44
VMBSX Martin Ratio Rank: 37

VBLLX

VBLLX Risk / Return Rank: 10
VBLLX Sharpe Ratio Rank: 10
VBLLX Sortino Ratio Rank: 10
VBLLX Omega Ratio Rank: 9
VBLLX Calmar Ratio Rank: 12
VBLLX Martin Ratio Rank: 10

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.

VMBSX vs. VBLLX - Risk-Adjusted Trends Comparison

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

	VMBSX	VBLLX	Difference
Sharpe ratio: Return per unit of total volatility	1.67	0.75	+0.92
Sortino ratio: Return per unit of downside risk	2.48	1.13	+1.35
Omega ratio: Gain probability vs. loss probability	1.31	1.13	+0.18
Calmar ratio: Return relative to maximum drawdown	2.36	1.01	+1.35
Martin ratio: Return relative to average drawdown	7.53	2.53	+4.99

VMBSX vs. VBLLX - Sharpe Ratio Comparison

The current VMBSX Sharpe Ratio is 1.67, which is higher than the VBLLX Sharpe Ratio of 0.75. The chart below compares the historical Sharpe Ratios of VMBSX and VBLLX, 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

VMBSX vs. VBLLX - Drawdown Comparison

The maximum VMBSX drawdown since its inception was -17.44%, smaller than the maximum VBLLX drawdown of -38.42%. Use the drawdown chart below to compare losses from any high point for VMBSX and VBLLX.

Drawdown Indicators

	VMBSX	VBLLX	Difference
Max Drawdown Largest peak-to-trough decline	-17.44%	-38.42%	+20.98%
Max Drawdown (1Y) Largest decline over 1 year	-2.67%	-5.98%	+3.31%
Max Drawdown (3Y) Largest decline over 3 years	-7.53%	-14.90%	+7.37%
Max Drawdown (5Y) Largest decline over 5 years	-17.12%	-36.29%	+19.17%
Max Drawdown (10Y) Largest decline over 10 years	-17.44%	-38.42%	+20.98%
Current Drawdown Current decline from peak	-1.00%	-24.15%	+23.15%
Average Drawdown Average peak-to-trough decline	-2.48%	-9.24%	+6.76%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.84%	2.39%	-1.55%

Volatility

VMBSX vs. VBLLX - Volatility Comparison

The current volatility for Vanguard Mortgage-Backed Securities Index Fund Admiral Shares (VMBSX) is 1.32%, while Vanguard Long-Term Bond Index Fund Institutional Shares (VBLLX) has a volatility of 2.08%. This indicates that VMBSX experiences smaller price fluctuations and is considered to be less risky than VBLLX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	VMBSX	VBLLX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.32%	2.08%	-0.76%
Volatility (6M) Calculated over the trailing 6-month period	2.84%	5.84%	-3.00%
Volatility (1Y) Calculated over the trailing 1-year period	3.76%	8.07%	-4.31%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	6.41%	12.87%	-6.46%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	4.86%	11.59%	-6.73%

VMBSX vs. VBLLX - Expense Ratio Comparison

VMBSX has a 0.07% expense ratio, which is higher than VBLLX's 0.05% 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

VMBSX vs. VBLLX - Dividend Comparison

VMBSX's dividend yield for the trailing twelve months is around 4.15%, less than VBLLX's 4.75% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
VBLLX Vanguard Long-Term Bond Index Fund Institutional Shares	4.75%	4.66%	4.64%	3.75%	4.16%	2.89%	5.84%	3.62%	3.82%	3.69%	4.19%	4.98%
VMBSX Vanguard Mortgage-Backed Securities Index Fund Admiral Shares	4.15%	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 VMBSX and VBLLX in my portfolio?

VMBSX and VBLLX have a correlation of 0.88, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, VMBSX or VBLLX?

VBLLX has higher volatility (2.08%) compared to VMBSX (1.32%). In terms of maximum drawdown, VMBSX dropped -17.44% vs VBLLX's -38.42%.

Which has better risk-adjusted returns?

VMBSX currently has the higher Sharpe Ratio (1.67 vs 0.75), 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.