VTSPX vs. APOIX
VTSPX (Vanguard Short-Term Inflation-Protected Securities Index Fund Institutional Shares) and APOIX (American Century Short Duration Inflation Protection Bond Fund Investor Class) are both Inflation-Protected Bonds funds. Over the past 10 years, VTSPX returned 3.16%/yr vs 3.13%/yr for APOIX. Their correlation of 0.88 suggests significant overlap in exposure. VTSPX charges 0.04%/yr vs 0.57%/yr for APOIX.
Performance
VTSPX vs. APOIX - Performance Comparison
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Returns By Period
The year-to-date returns for both stocks are quite close, with VTSPX having a 2.06% return and APOIX slightly lower at 2.02%. Both investments have delivered pretty close results over the past 10 years, with VTSPX having a 3.16% annualized return and APOIX not far behind at 3.13%.
VTSPX
- 1D
- 0.00%
- 1M
- 0.04%
- YTD
- 2.06%
- 6M
- 2.05%
- 1Y
- 4.72%
- 3Y*
- 5.26%
- 5Y*
- 3.40%
- 10Y*
- 3.16%
APOIX
- 1D
- 0.00%
- 1M
- -0.00%
- YTD
- 2.02%
- 6M
- 1.90%
- 1Y
- 4.51%
- 3Y*
- 4.85%
- 5Y*
- 2.96%
- 10Y*
- 3.13%
VTSPX vs. APOIX - Yearly Performance Comparison
| 2026 (YTD) | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | |
|---|---|---|---|---|---|---|---|---|---|---|
VTSPX Vanguard Short-Term Inflation-Protected Securities Index Fund Institutional Shares | 2.06% | 6.06% | 4.75% | 4.61% | -2.82% | 5.32% | 4.99% | 4.82% | 0.59% | 0.83% |
APOIX American Century Short Duration Inflation Protection Bond Fund Investor Class | 2.02% | 5.95% | 4.15% | 3.82% | -3.89% | 6.30% | 5.06% | 4.77% | 1.81% | 0.73% |
Correlation
The correlation between VTSPX and APOIX is 0.86, 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 | 0.86 |
Correlation (3Y) Calculated over the trailing 3-year period | 0.91 |
Correlation (5Y) Calculated over the trailing 5-year period | 0.92 |
Correlation (10Y) Calculated over the trailing 10-year period | 0.88 |
Correlation (All Time) Calculated using the full available price history since Jan 3, 2013 | 0.88 |
The correlation between VTSPX and APOIX has been stable across timeframes, ranging from 0.86 to 0.92 - a consistent structural relationship.
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Return for Risk
VTSPX vs. APOIX — Risk / Return Rank
VTSPX
APOIX
VTSPX vs. APOIX - Risk-Adjusted Trends Comparison
This table presents a comparison of risk-adjusted performance metrics for Vanguard Short-Term Inflation-Protected Securities Index Fund Institutional Shares (VTSPX) and American Century Short Duration Inflation Protection Bond Fund Investor Class (APOIX). 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.
| VTSPX | APOIX | Difference | |
|---|---|---|---|
| Sharpe ratioReturn per unit of total volatility | +0.60 | ||
| Sortino ratioReturn per unit of downside risk | +1.19 | ||
| Omega ratioGain probability vs. loss probability | 1.67 | 1.51 | +0.16 |
| Calmar ratioReturn relative to maximum drawdown | 6.50 | 5.81 | +0.69 |
| Martin ratioReturn relative to average drawdown | 25.54 | 19.09 | +6.45 |
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month. | |||
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Sharpe Ratios by Period
| VTSPX | APOIX | Difference | |
|---|---|---|---|
Sharpe Ratio (1Y)Calculated over the trailing 1-year period | 3.06 | 2.45 | +0.60 |
Sharpe Ratio (5Y)Calculated over the trailing 5-year period | 1.28 | 0.90 | +0.38 |
Sharpe Ratio (10Y)Calculated over the trailing 10-year period | 1.42 | 1.10 | +0.32 |
Sharpe Ratio (All Time)Calculated using the full available price history | 1.08 | 0.72 | +0.37 |
Drawdowns
VTSPX vs. APOIX - Drawdown Comparison
The maximum VTSPX drawdown since its inception was -5.35%, smaller than the maximum APOIX drawdown of -14.54%. Use the drawdown chart below to compare losses from any high point for VTSPX and APOIX.
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Drawdown Indicators
| VTSPX | APOIX | Difference | |
|---|---|---|---|
Max DrawdownLargest peak-to-trough decline | -5.35% | -14.54% | +9.19% |
Max Drawdown (1Y)Largest decline over 1 year | -0.72% | -0.76% | +0.04% |
Max Drawdown (3Y)Largest decline over 3 years | -0.92% | -1.42% | +0.50% |
Max Drawdown (5Y)Largest decline over 5 years | -5.35% | -6.58% | +1.23% |
Max Drawdown (10Y)Largest decline over 10 years | -5.35% | -6.58% | +1.23% |
Current DrawdownCurrent decline from peak | -0.04% | -0.00% | -0.04% |
Average DrawdownAverage peak-to-trough decline | -1.01% | -1.99% | +0.98% |
Ulcer IndexDepth and duration of drawdowns from previous peaks | 0.18% | 0.23% | -0.05% |
Volatility
VTSPX vs. APOIX - Volatility Comparison
Vanguard Short-Term Inflation-Protected Securities Index Fund Institutional Shares (VTSPX) has a higher volatility of 0.57% compared to American Century Short Duration Inflation Protection Bond Fund Investor Class (APOIX) at 0.51%. This indicates that VTSPX's price experiences larger fluctuations and is considered to be riskier than APOIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.
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Volatility by Period
| VTSPX | APOIX | Difference | |
|---|---|---|---|
Volatility (1M)Calculated over the trailing 1-month period | 0.57% | 0.51% | +0.06% |
Volatility (6M)Calculated over the trailing 6-month period | 1.12% | 1.25% | -0.13% |
Volatility (1Y)Calculated over the trailing 1-year period | 1.52% | 1.81% | -0.29% |
Volatility (5Y)Calculated over the trailing 5-year period, annualized | 2.67% | 3.31% | -0.64% |
Volatility (10Y)Calculated over the trailing 10-year period, annualized | 2.23% | 2.85% | -0.62% |
VTSPX vs. APOIX - Expense Ratio Comparison
VTSPX has a 0.04% expense ratio, which is lower than APOIX's 0.57% expense ratio.
Dividends
VTSPX vs. APOIX - Dividend Comparison
VTSPX's dividend yield for the trailing twelve months is around 3.59%, less than APOIX's 3.91% yield.
| Position | TTM | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 |
|---|---|---|---|---|---|---|---|---|---|---|---|
APOIX American Century Short Duration Inflation Protection Bond Fund Investor Class | 3.91% | 3.99% | 2.31% | 2.78% | 5.63% | 3.92% | 0.81% | 1.69% | 3.99% | 1.52% | 0.42% |
VTSPX Vanguard Short-Term Inflation-Protected Securities Index Fund Institutional Shares | 3.59% | 3.81% | 2.70% | 2.86% | 6.84% | 4.69% | 1.21% | 1.96% | 2.47% | 1.52% | 0.80% |
Frequently Asked Questions
VTSPX and APOIX have a correlation of 0.86, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.
VTSPX has higher volatility (0.57%) compared to APOIX (0.51%). In terms of maximum drawdown, VTSPX dropped -5.35% vs APOIX's -14.54%.
VTSPX currently has the higher Sharpe Ratio (3.06 vs 2.45), 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.
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