VSBIX vs. TWUSX

Last updated Jun 6, 2026

VSBIX (Vanguard Short-Term Treasury Index Fund Institutional Shares) and TWUSX (American Century Short-Term Government Fund) are both Government Bonds funds. Over the past 10 years, VSBIX returned 1.78%/yr vs 1.51%/yr for TWUSX. A 0.73 correlation means they provide meaningful diversification when combined. VSBIX charges 0.05%/yr vs 0.55%/yr for TWUSX.

Performance

VSBIX vs. TWUSX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Vanguard Short-Term Treasury Index Fund Institutional Shares (VSBIX) and American Century Short-Term Government Fund (TWUSX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, VSBIX achieves a 0.57% return, which is significantly higher than TWUSX's 0.36% return. Over the past 10 years, VSBIX has outperformed TWUSX with an annualized return of 1.78%, while TWUSX has yielded a comparatively lower 1.51% annualized return.

VSBIX

• 1D: 0.08%
• 1M: -0.01%
• YTD: 0.57%
• 6M: 0.93%
• 1Y: 3.44%
• 3Y*: 4.29%
• 5Y*: 1.89%
• 10Y*: 1.78%

TWUSX

• 1D: 0.00%
• 1M: -0.12%
• YTD: 0.36%
• 6M: 0.77%
• 1Y: 3.19%
• 3Y*: 3.83%
• 5Y*: 1.48%
• 10Y*: 1.51%

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

VSBIX vs. TWUSX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
VSBIX Vanguard Short-Term Treasury Index Fund Institutional Shares	0.57%	5.11%	4.37%	4.28%	-3.87%	-0.67%	3.11%	3.53%	1.52%	0.40%
TWUSX American Century Short-Term Government Fund	0.36%	4.94%	3.59%	3.70%	-4.31%	-0.09%	3.36%	2.91%	1.12%	0.22%

Correlation

The correlation between VSBIX and TWUSX 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	0.82
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 Nov 24, 2009	0.73

The correlation between VSBIX and TWUSX shifts across timeframes, from 0.73 (all time) to 0.83 (5 years), reflecting how their relationship changes across market environments.

Return for Risk

VSBIX vs. TWUSX — Risk / Return Rank

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

VSBIX

VSBIX Risk / Return Rank: 87
VSBIX Sharpe Ratio Rank: 83
VSBIX Sortino Ratio Rank: 91
VSBIX Omega Ratio Rank: 84
VSBIX Calmar Ratio Rank: 88
VSBIX Martin Ratio Rank: 90

TWUSX

TWUSX Risk / Return Rank: 55
TWUSX Sharpe Ratio Rank: 38
TWUSX Sortino Ratio Rank: 56
TWUSX Omega Ratio Rank: 51
TWUSX Calmar Ratio Rank: 71
TWUSX Martin Ratio Rank: 57

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.

VSBIX vs. TWUSX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Vanguard Short-Term Treasury Index Fund Institutional Shares (VSBIX) and American Century Short-Term Government Fund (TWUSX). 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.

	VSBIX	TWUSX	Difference
Sharpe ratio: Return per unit of total volatility	2.67	1.72	+0.95
Sortino ratio: Return per unit of downside risk	4.46	3.07	+1.39
Omega ratio: Gain probability vs. loss probability	1.56	1.38	+0.18
Calmar ratio: Return relative to maximum drawdown	4.18	3.16	+1.02
Martin ratio: Return relative to average drawdown	17.23	11.07	+6.16
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

VSBIX vs. TWUSX - Sharpe Ratio Comparison

The current VSBIX Sharpe Ratio is 2.67, which is higher than the TWUSX Sharpe Ratio of 1.72. The chart below compares the historical Sharpe Ratios of VSBIX and TWUSX, 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

	VSBIX	TWUSX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.67	1.72	+0.95
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.97	0.65	+0.33
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	1.16	0.83	+0.33
Sharpe Ratio (All Time) Calculated using the full available price history	1.09	-0.00	+1.09

Drawdowns

VSBIX vs. TWUSX - Drawdown Comparison

The maximum VSBIX drawdown since its inception was -5.74%, smaller than the maximum TWUSX drawdown of -91.06%. Use the drawdown chart below to compare losses from any high point for VSBIX and TWUSX.

Drawdown Indicators

	VSBIX	TWUSX	Difference
Max Drawdown Largest peak-to-trough decline	-5.74%	-91.06%	+85.32%
Max Drawdown (1Y) Largest decline over 1 year	-0.81%	-0.98%	+0.17%
Max Drawdown (3Y) Largest decline over 3 years	-0.81%	-1.09%	+0.28%
Max Drawdown (5Y) Largest decline over 5 years	-5.74%	-5.81%	+0.07%
Max Drawdown (10Y) Largest decline over 10 years	-5.74%	-5.85%	+0.11%
Current Drawdown Current decline from peak	-0.16%	-64.62%	+64.46%
Average Drawdown Average peak-to-trough decline	-0.59%	-76.97%	+76.38%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.20%	0.28%	-0.08%

Volatility

VSBIX vs. TWUSX - Volatility Comparison

The current volatility for Vanguard Short-Term Treasury Index Fund Institutional Shares (VSBIX) is 0.39%, while American Century Short-Term Government Fund (TWUSX) has a volatility of 0.49%. This indicates that VSBIX experiences smaller price fluctuations and is considered to be less risky than TWUSX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	VSBIX	TWUSX	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.39%	0.49%	-0.10%
Volatility (6M) Calculated over the trailing 6-month period	0.86%	1.23%	-0.37%
Volatility (1Y) Calculated over the trailing 1-year period	1.27%	1.81%	-0.54%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	1.95%	2.31%	-0.36%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	1.53%	1.82%	-0.29%

VSBIX vs. TWUSX - Expense Ratio Comparison

VSBIX has a 0.05% expense ratio, which is lower than TWUSX's 0.55% expense ratio.

Dividends

VSBIX vs. TWUSX - Dividend Comparison

VSBIX's dividend yield for the trailing twelve months is around 3.87%, more than TWUSX's 3.60% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
TWUSX American Century Short-Term Government Fund	3.60%	3.70%	4.06%	3.83%	1.12%	1.05%	0.72%	1.81%	1.74%	1.06%	0.57%	0.53%
VSBIX Vanguard Short-Term Treasury Index Fund Institutional Shares	3.87%	3.99%	4.52%	3.31%	1.14%	0.65%	1.74%	2.28%	1.81%	1.11%	0.80%	0.74%

Frequently Asked Questions

Can I hold both VSBIX and TWUSX in my portfolio?

VSBIX and TWUSX 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, VSBIX or TWUSX?

TWUSX has higher volatility (0.49%) compared to VSBIX (0.39%). In terms of maximum drawdown, VSBIX dropped -5.74% vs TWUSX's -91.06%.

Which has better risk-adjusted returns?

VSBIX currently has the higher Sharpe Ratio (2.67 vs 1.72), 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.