VCOBX vs. VTBNX

Last updated Jun 5, 2026

VCOBX (Vanguard Core Bond Fund Admiral Shares) and VTBNX (Vanguard Total Bond Market II Index Fund) are both Total Bond Market funds from Vanguard. Over the past 10 years, VCOBX returned 2.17%/yr vs 1.53%/yr for VTBNX. With a 0.96 correlation, they move nearly in lockstep. VCOBX charges 0.10%/yr vs 0.02%/yr for VTBNX.

Performance

VCOBX vs. VTBNX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Vanguard Core Bond Fund Admiral Shares (VCOBX) and Vanguard Total Bond Market II Index Fund (VTBNX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, VCOBX achieves a 0.43% return, which is significantly higher than VTBNX's 0.12% return. Over the past 10 years, VCOBX has outperformed VTBNX with an annualized return of 2.17%, while VTBNX has yielded a comparatively lower 1.53% annualized return.

VCOBX

• 1D: -0.17%
• 1M: 0.16%
• YTD: 0.43%
• 6M: 0.52%
• 1Y: 4.91%
• 3Y*: 4.84%
• 5Y*: 0.55%
• 10Y*: 2.17%

VTBNX

• 1D: -0.21%
• 1M: 0.14%
• YTD: 0.12%
• 6M: 0.25%
• 1Y: 4.44%
• 3Y*: 3.94%
• 5Y*: 0.09%
• 10Y*: 1.53%

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

VCOBX vs. VTBNX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
VCOBX Vanguard Core Bond Fund Admiral Shares	0.43%	7.73%	2.21%	6.39%	-13.13%	-1.51%	10.41%	9.64%	-0.85%	3.89%
VTBNX Vanguard Total Bond Market II Index Fund	0.12%	7.18%	1.32%	5.68%	-13.12%	-1.82%	7.39%	8.71%	-0.27%	3.62%

Correlation

The correlation between VCOBX and VTBNX 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	0.96
Correlation (5Y) Calculated over the trailing 5-year period	0.97
Correlation (10Y) Calculated over the trailing 10-year period	0.96
Correlation (All Time) Calculated using the full available price history since Mar 31, 2016	0.96

The correlation between VCOBX and VTBNX has been stable across timeframes, ranging from 0.91 to 0.97 - a consistent structural relationship.

Return for Risk

VCOBX vs. VTBNX — Risk / Return Rank

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

VCOBX

VCOBX Risk / Return Rank: 28
VCOBX Sharpe Ratio Rank: 28
VCOBX Sortino Ratio Rank: 29
VCOBX Omega Ratio Rank: 27
VCOBX Calmar Ratio Rank: 33
VCOBX Martin Ratio Rank: 26

VTBNX

VTBNX Risk / Return Rank: 21
VTBNX Sharpe Ratio Rank: 20
VTBNX Sortino Ratio Rank: 22
VTBNX Omega Ratio Rank: 18
VTBNX Calmar Ratio Rank: 23
VTBNX Martin Ratio Rank: 20

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.

VCOBX vs. VTBNX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Vanguard Core Bond Fund Admiral Shares (VCOBX) and Vanguard Total Bond Market II Index Fund (VTBNX). 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.

	VCOBX	VTBNX	Difference
Sharpe ratio: Return per unit of total volatility	1.52	1.28	+0.24
Sortino ratio: Return per unit of downside risk	2.26	1.94	+0.32
Omega ratio: Gain probability vs. loss probability	1.27	1.22	+0.05
Calmar ratio: Return relative to maximum drawdown	2.13	1.77	+0.36
Martin ratio: Return relative to average drawdown	6.33	5.27	+1.06
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

VCOBX vs. VTBNX - Sharpe Ratio Comparison

The current VCOBX Sharpe Ratio is 1.52, which is comparable to the VTBNX Sharpe Ratio of 1.28. The chart below compares the historical Sharpe Ratios of VCOBX and VTBNX, 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

	VCOBX	VTBNX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.52	1.28	+0.24
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.10	0.02	+0.08
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.46	0.31	+0.15
Sharpe Ratio (All Time) Calculated using the full available price history	0.48	0.37	+0.11

Drawdowns

VCOBX vs. VTBNX - Drawdown Comparison

The maximum VCOBX drawdown since its inception was -18.14%, roughly equal to the maximum VTBNX drawdown of -18.71%. Use the drawdown chart below to compare losses from any high point for VCOBX and VTBNX.

Drawdown Indicators

	VCOBX	VTBNX	Difference
Max Drawdown Largest peak-to-trough decline	-18.14%	-18.71%	+0.57%
Max Drawdown (1Y) Largest decline over 1 year	-2.62%	-2.83%	+0.21%
Max Drawdown (3Y) Largest decline over 3 years	-5.63%	-5.97%	+0.34%
Max Drawdown (5Y) Largest decline over 5 years	-18.03%	-18.05%	+0.02%
Max Drawdown (10Y) Largest decline over 10 years	-18.14%	-18.71%	+0.57%
Current Drawdown Current decline from peak	-1.41%	-2.41%	+1.00%
Average Drawdown Average peak-to-trough decline	-4.18%	-4.87%	+0.69%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.88%	0.95%	-0.07%

Volatility

VCOBX vs. VTBNX - Volatility Comparison

Vanguard Core Bond Fund Admiral Shares (VCOBX) and Vanguard Total Bond Market II Index Fund (VTBNX) have volatilities of 1.29% and 1.31%, respectively, indicating that both stocks experience similar levels of price fluctuations. This suggests that the risk associated with both stocks, as measured by volatility, is nearly the same. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	VCOBX	VTBNX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.29%	1.31%	-0.02%
Volatility (6M) Calculated over the trailing 6-month period	2.63%	2.78%	-0.15%
Volatility (1Y) Calculated over the trailing 1-year period	3.67%	3.92%	-0.25%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	5.78%	5.96%	-0.18%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	4.76%	4.93%	-0.17%

VCOBX vs. VTBNX - Expense Ratio Comparison

VCOBX has a 0.10% expense ratio, which is higher than VTBNX's 0.02% 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

VCOBX vs. VTBNX - Dividend Comparison

VCOBX's dividend yield for the trailing twelve months is around 4.74%, more than VTBNX's 4.06% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016
VCOBX Vanguard Core Bond Fund Admiral Shares	4.74%	4.80%	5.04%	4.44%	3.01%	1.23%	3.09%	3.08%	3.10%	2.20%	2.29%
VTBNX Vanguard Total Bond Market II Index Fund	4.06%	3.95%	3.77%	3.13%	2.54%	1.82%	3.12%	2.79%	2.56%	2.52%	2.55%

Frequently Asked Questions

Can I hold both VCOBX and VTBNX in my portfolio?

With a correlation of 0.91, VCOBX and VTBNX 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, VCOBX or VTBNX?

VTBNX has higher volatility (1.31%) compared to VCOBX (1.29%). In terms of maximum drawdown, VCOBX dropped -18.14% vs VTBNX's -18.71%.

Which has better risk-adjusted returns?

VCOBX currently has the higher Sharpe Ratio (1.52 vs 1.28), 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.