CPTNX vs. VEDTX

Last updated Jun 26, 2026

CPTNX (American Century Government Bond Fund) and VEDTX (Vanguard Extended Duration Treasury Index Fund) are both Government Bonds funds. Over the past 10 years, CPTNX returned 0.83%/yr vs -3.27%/yr for VEDTX. Their correlation of 0.83 suggests significant overlap in exposure. CPTNX charges 0.47%/yr vs 0.06%/yr for VEDTX.

Performance

CPTNX vs. VEDTX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in American Century Government Bond Fund (CPTNX) and Vanguard Extended Duration Treasury Index Fund (VEDTX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, CPTNX achieves a 0.32% return, which is significantly lower than VEDTX's 2.84% return. Over the past 10 years, CPTNX has outperformed VEDTX with an annualized return of 0.83%, while VEDTX has yielded a comparatively lower -3.27% annualized return.

CPTNX

• 1D: 0.54%
• 1M: 0.77%
• YTD: 0.32%
• 6M: 0.55%
• 1Y: 4.17%
• 3Y*: 3.34%
• 5Y*: -0.49%
• 10Y*: 0.83%

VEDTX

• 1D: 2.10%
• 1M: 5.11%
• YTD: 2.84%
• 6M: 1.60%
• 1Y: 4.89%
• 3Y*: -4.66%
• 5Y*: -9.78%
• 10Y*: -3.27%

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

CPTNX vs. VEDTX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
CPTNX American Century Government Bond Fund	0.32%	7.26%	0.32%	3.51%	-13.10%	-1.24%	6.71%	6.16%	0.57%	2.15%
VEDTX Vanguard Extended Duration Treasury Index Fund	2.84%	1.34%	-13.35%	2.15%	-39.40%	-6.52%	24.20%	19.16%	-3.50%	12.69%

Correlation

The correlation between CPTNX and VEDTX is 0.77, 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	0.77
Correlation (3Y) Calculated over the trailing 3-year period	0.84
Correlation (5Y) Calculated over the trailing 5-year period	0.85
Correlation (10Y) Calculated over the trailing 10-year period	0.85
Correlation (All Time) Calculated using the full available price history since Nov 20, 2007	0.83

The correlation between CPTNX and VEDTX has been stable across timeframes, ranging from 0.77 to 0.85 - a consistent structural relationship.

Return for Risk

CPTNX vs. VEDTX — Risk / Return Rank

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

CPTNX

CPTNX Risk / Return Rank: 19
CPTNX Sharpe Ratio Rank: 20
CPTNX Sortino Ratio Rank: 21
CPTNX Omega Ratio Rank: 19
CPTNX Calmar Ratio Rank: 18
CPTNX Martin Ratio Rank: 17

VEDTX

VEDTX Risk / Return Rank: 6
VEDTX Sharpe Ratio Rank: 6
VEDTX Sortino Ratio Rank: 6
VEDTX Omega Ratio Rank: 6
VEDTX Calmar Ratio Rank: 6
VEDTX Martin Ratio Rank: 6

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.

CPTNX vs. VEDTX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for American Century Government Bond Fund (CPTNX) and Vanguard Extended Duration Treasury Index Fund (VEDTX). 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.

	CPTNX	VEDTX	Difference
Sharpe ratio: Return per unit of total volatility	1.04	0.35	+0.69
Sortino ratio: Return per unit of downside risk	1.57	0.61	+0.96
Omega ratio: Gain probability vs. loss probability	1.18	1.07	+0.12
Calmar ratio: Return relative to maximum drawdown	1.25	0.41	+0.84
Martin ratio: Return relative to average drawdown	3.61	0.91	+2.70

CPTNX vs. VEDTX - Sharpe Ratio Comparison

The current CPTNX Sharpe Ratio is 1.04, which is higher than the VEDTX Sharpe Ratio of 0.35. The chart below compares the historical Sharpe Ratios of CPTNX and VEDTX, 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

CPTNX vs. VEDTX - Drawdown Comparison

The maximum CPTNX drawdown since its inception was -19.73%, smaller than the maximum VEDTX drawdown of -60.00%. Use the drawdown chart below to compare losses from any high point for CPTNX and VEDTX.

Drawdown Indicators

	CPTNX	VEDTX	Difference
Max Drawdown Largest peak-to-trough decline	-19.73%	-60.00%	+40.27%
Max Drawdown (1Y) Largest decline over 1 year	-3.36%	-12.41%	+9.05%
Max Drawdown (3Y) Largest decline over 3 years	-7.26%	-26.95%	+19.69%
Max Drawdown (5Y) Largest decline over 5 years	-19.15%	-55.15%	+36.00%
Max Drawdown (10Y) Largest decline over 10 years	-19.73%	-60.00%	+40.27%
Current Drawdown Current decline from peak	-4.79%	-52.72%	+47.93%
Average Drawdown Average peak-to-trough decline	-2.29%	-23.58%	+21.29%
Ulcer Index Depth and duration of drawdowns from previous peaks	1.16%	5.56%	-4.40%

Volatility

CPTNX vs. VEDTX - Volatility Comparison

The current volatility for American Century Government Bond Fund (CPTNX) is 1.30%, while Vanguard Extended Duration Treasury Index Fund (VEDTX) has a volatility of 3.78%. This indicates that CPTNX experiences smaller price fluctuations and is considered to be less risky than VEDTX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	CPTNX	VEDTX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.30%	3.78%	-2.48%
Volatility (6M) Calculated over the trailing 6-month period	3.05%	10.10%	-7.05%
Volatility (1Y) Calculated over the trailing 1-year period	4.04%	14.49%	-10.45%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	6.31%	21.85%	-15.54%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	4.99%	20.10%	-15.11%

CPTNX vs. VEDTX - Expense Ratio Comparison

CPTNX has a 0.47% expense ratio, which is higher than VEDTX's 0.06% expense ratio.

Dividends

CPTNX vs. VEDTX - Dividend Comparison

CPTNX's dividend yield for the trailing twelve months is around 4.00%, less than VEDTX's 4.81% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
CPTNX American Century Government Bond Fund	4.00%	4.07%	4.22%	3.72%	1.84%	2.10%	2.09%	2.48%	2.49%	2.14%	2.28%	1.69%
VEDTX Vanguard Extended Duration Treasury Index Fund	4.81%	4.94%	4.68%	3.55%	3.30%	1.96%	5.56%	3.53%	2.94%	2.23%	5.34%	4.28%

Frequently Asked Questions

Can I hold both CPTNX and VEDTX in my portfolio?

CPTNX and VEDTX have a correlation of 0.77, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, CPTNX or VEDTX?

VEDTX has higher volatility (3.78%) compared to CPTNX (1.30%). In terms of maximum drawdown, CPTNX dropped -19.73% vs VEDTX's -60.00%.

Which has better risk-adjusted returns?

CPTNX currently has the higher Sharpe Ratio (1.04 vs 0.35), 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.