VSTBX vs. CPUIX

Last updated Jun 4, 2026

VSTBX (Vanguard Short-Term Corporate Bond Index Fund Institutional Shares) and CPUIX (AAM/Insight Select Income Fund) are both Corporate Bonds funds. Over the past 10 years, VSTBX returned 3.01%/yr vs 2.79%/yr for CPUIX. A 0.76 correlation means they provide meaningful diversification when combined. VSTBX charges 0.05%/yr vs 0.57%/yr for CPUIX.

Performance

VSTBX vs. CPUIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Vanguard Short-Term Corporate Bond Index Fund Institutional Shares (VSTBX) and AAM/Insight Select Income Fund (CPUIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, VSTBX achieves a 0.73% return, which is significantly higher than CPUIX's 0.54% return. Over the past 10 years, VSTBX has outperformed CPUIX with an annualized return of 3.01%, while CPUIX has yielded a comparatively lower 2.79% annualized return.

VSTBX

• 1D: 0.00%
• 1M: 0.30%
• YTD: 0.73%
• 6M: 1.00%
• 1Y: 4.66%
• 3Y*: 5.68%
• 5Y*: 2.43%
• 10Y*: 3.01%

CPUIX

• 1D: 0.11%
• 1M: 0.83%
• YTD: 0.54%
• 6M: 0.46%
• 1Y: 6.36%
• 3Y*: 5.09%
• 5Y*: 0.38%
• 10Y*: 2.79%

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

VSTBX vs. CPUIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
VSTBX Vanguard Short-Term Corporate Bond Index Fund Institutional Shares	0.73%	6.75%	5.37%	6.17%	-5.73%	-0.41%	5.07%	9.68%	0.92%	2.48%
CPUIX AAM/Insight Select Income Fund	0.54%	6.59%	2.61%	8.40%	-16.27%	-0.12%	10.20%	14.81%	-3.01%	6.86%

Correlation

The correlation between VSTBX and CPUIX is 0.78, 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	0.78
Correlation (3Y) Calculated over the trailing 3-year period	0.83
Correlation (5Y) Calculated over the trailing 5-year period	0.81
Correlation (10Y) Calculated over the trailing 10-year period	0.77
Correlation (All Time) Calculated using the full available price history since Jan 3, 2014	0.76

The correlation between VSTBX and CPUIX has been stable across timeframes, ranging from 0.76 to 0.83 - a consistent structural relationship.

Return for Risk

VSTBX vs. CPUIX — Risk / Return Rank

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

VSTBX

VSTBX Risk / Return Rank: 81
VSTBX Sharpe Ratio Rank: 82
VSTBX Sortino Ratio Rank: 87
VSTBX Omega Ratio Rank: 81
VSTBX Calmar Ratio Rank: 78
VSTBX Martin Ratio Rank: 76

CPUIX

CPUIX Risk / Return Rank: 30
CPUIX Sharpe Ratio Rank: 30
CPUIX Sortino Ratio Rank: 31
CPUIX Omega Ratio Rank: 29
CPUIX Calmar Ratio Rank: 30
CPUIX Martin Ratio Rank: 28

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.

VSTBX vs. CPUIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Vanguard Short-Term Corporate Bond Index Fund Institutional Shares (VSTBX) and AAM/Insight Select Income Fund (CPUIX). 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.

	VSTBX	CPUIX	Difference
Sharpe ratio: Return per unit of total volatility	2.67	1.57	+1.10
Sortino ratio: Return per unit of downside risk	4.17	2.33	+1.84
Omega ratio: Gain probability vs. loss probability	1.54	1.28	+0.25
Calmar ratio: Return relative to maximum drawdown	3.57	2.05	+1.51
Martin ratio: Return relative to average drawdown	14.23	6.61	+7.63
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

VSTBX vs. CPUIX - Sharpe Ratio Comparison

The current VSTBX Sharpe Ratio is 2.67, which is higher than the CPUIX Sharpe Ratio of 1.57. The chart below compares the historical Sharpe Ratios of VSTBX and CPUIX, 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

	VSTBX	CPUIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.67	1.57	+1.10
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.90	0.06	+0.83
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	1.27	0.51	+0.76
Sharpe Ratio (All Time) Calculated using the full available price history	1.47	0.64	+0.82

Drawdowns

VSTBX vs. CPUIX - Drawdown Comparison

The maximum VSTBX drawdown since its inception was -9.34%, smaller than the maximum CPUIX drawdown of -22.37%. Use the drawdown chart below to compare losses from any high point for VSTBX and CPUIX.

Drawdown Indicators

	VSTBX	CPUIX	Difference
Max Drawdown Largest peak-to-trough decline	-9.34%	-22.37%	+13.03%
Max Drawdown (1Y) Largest decline over 1 year	-1.31%	-3.22%	+1.91%
Max Drawdown (3Y) Largest decline over 3 years	-1.31%	-6.03%	+4.72%
Max Drawdown (5Y) Largest decline over 5 years	-9.34%	-22.37%	+13.03%
Max Drawdown (10Y) Largest decline over 10 years	-9.34%	-22.37%	+13.03%
Current Drawdown Current decline from peak	-0.24%	-1.68%	+1.44%
Average Drawdown Average peak-to-trough decline	-0.96%	-4.47%	+3.51%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.33%	1.00%	-0.67%

Volatility

VSTBX vs. CPUIX - Volatility Comparison

The current volatility for Vanguard Short-Term Corporate Bond Index Fund Institutional Shares (VSTBX) is 0.57%, while AAM/Insight Select Income Fund (CPUIX) has a volatility of 1.55%. This indicates that VSTBX experiences smaller price fluctuations and is considered to be less risky than CPUIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	VSTBX	CPUIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.57%	1.55%	-0.98%
Volatility (6M) Calculated over the trailing 6-month period	1.27%	3.07%	-1.80%
Volatility (1Y) Calculated over the trailing 1-year period	1.76%	4.22%	-2.46%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	2.71%	5.99%	-3.28%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	2.38%	5.52%	-3.14%

VSTBX vs. CPUIX - Expense Ratio Comparison

VSTBX has a 0.05% expense ratio, which is lower than CPUIX's 0.57% expense ratio.

Dividends

VSTBX vs. CPUIX - Dividend Comparison

VSTBX's dividend yield for the trailing twelve months is around 4.44%, less than CPUIX's 4.79% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
CPUIX AAM/Insight Select Income Fund	4.79%	3.53%	3.81%	3.61%	3.98%	3.15%	3.83%	3.19%	3.80%	3.12%	3.21%	3.29%
VSTBX Vanguard Short-Term Corporate Bond Index Fund Institutional Shares	4.44%	4.34%	4.29%	3.09%	2.00%	1.80%	2.27%	5.40%	2.67%	2.27%	1.96%	2.25%

Frequently Asked Questions

Can I hold both VSTBX and CPUIX in my portfolio?

VSTBX and CPUIX have a correlation of 0.78, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, VSTBX or CPUIX?

CPUIX has higher volatility (1.55%) compared to VSTBX (0.57%). In terms of maximum drawdown, VSTBX dropped -9.34% vs CPUIX's -22.37%.

Which has better risk-adjusted returns?

VSTBX currently has the higher Sharpe Ratio (2.67 vs 1.57), 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.