VTSPX vs. VIIIX
VTSPX (Vanguard Short-Term Inflation-Protected Securities Index Fund Institutional Shares) and VIIIX (Vanguard Institutional Index Fund Institutional Plus Shares) are both mutual funds - VTSPX is a Inflation-Protected Bonds fund managed by Vanguard, while VIIIX is a S&P 500 fund tracking the S&P 500 Index. Over the past 10 years, VTSPX returned 3.10%/yr vs 15.32%/yr for VIIIX. At a 0.06 correlation, their price movements are largely independent. VTSPX charges 0.04%/yr vs 0.02%/yr for VIIIX.
Performance
VTSPX vs. VIIIX - Performance Comparison
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Returns By Period
In the year-to-date period, VTSPX achieves a 1.70% return, which is significantly lower than VIIIX's 8.42% return. Over the past 10 years, VTSPX has underperformed VIIIX with an annualized return of 3.10%, while VIIIX has yielded a comparatively higher 15.32% annualized return.
VTSPX
- 1D
- -0.28%
- 1M
- -0.16%
- YTD
- 1.70%
- 6M
- 1.81%
- 1Y
- 4.60%
- 3Y*
- 5.10%
- 5Y*
- 3.30%
- 10Y*
- 3.10%
VIIIX
- 1D
- -2.63%
- 1M
- -0.08%
- YTD
- 8.42%
- 6M
- 8.48%
- 1Y
- 24.54%
- 3Y*
- 21.94%
- 5Y*
- 13.54%
- 10Y*
- 15.32%
VTSPX vs. VIIIX - 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 | 1.70% | 6.06% | 4.75% | 4.61% | -2.82% | 5.32% | 4.99% | 4.82% | 0.59% | 0.83% |
VIIIX Vanguard Institutional Index Fund Institutional Plus Shares | 8.42% | 17.87% | 26.29% | 25.79% | -18.14% | 28.69% | 18.41% | 31.48% | -4.41% | 21.82% |
Correlation
The correlation between VTSPX and VIIIX is -0.02, meaning there is essentially no relationship between their price movements. Each responds to its own set of market drivers, making them strong candidates for combining in a diversified portfolio.
| Correlation | |
|---|---|
Correlation (1Y) Calculated over the trailing 1-year period | -0.02 |
Correlation (3Y) Calculated over the trailing 3-year period | 0.09 |
Correlation (5Y) Calculated over the trailing 5-year period | 0.14 |
Correlation (10Y) Calculated over the trailing 10-year period | 0.08 |
Correlation (All Time) Calculated using the full available price history since Jan 3, 2013 | 0.06 |
The correlation between VTSPX and VIIIX shifts across timeframes, from -0.02 (1 year) to 0.14 (5 years), reflecting how their relationship changes across market environments.
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Return for Risk
VTSPX vs. VIIIX — Risk / Return Rank
VTSPX
VIIIX
VTSPX vs. VIIIX - 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 Vanguard Institutional Index Fund Institutional Plus Shares (VIIIX). 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 | VIIIX | Difference | |
|---|---|---|---|
| Sharpe ratioReturn per unit of total volatility | +0.72 | ||
| Sortino ratioReturn per unit of downside risk | +1.86 | ||
| Omega ratioGain probability vs. loss probability | 1.62 | 1.39 | +0.23 |
| Calmar ratioReturn relative to maximum drawdown | 6.15 | 2.92 | +3.23 |
| Martin ratioReturn relative to average drawdown | 24.47 | 13.57 | +10.90 |
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 | VIIIX | Difference | |
|---|---|---|---|
Sharpe Ratio (1Y)Calculated over the trailing 1-year period | 2.85 | 2.13 | +0.72 |
Sharpe Ratio (5Y)Calculated over the trailing 5-year period | 1.24 | 0.80 | +0.44 |
Sharpe Ratio (10Y)Calculated over the trailing 10-year period | 1.39 | 0.85 | +0.54 |
Sharpe Ratio (All Time)Calculated using the full available price history | 1.07 | 0.49 | +0.58 |
Drawdowns
VTSPX vs. VIIIX - Drawdown Comparison
The maximum VTSPX drawdown since its inception was -5.35%, smaller than the maximum VIIIX drawdown of -55.18%. Use the drawdown chart below to compare losses from any high point for VTSPX and VIIIX.
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Drawdown Indicators
| VTSPX | VIIIX | Difference | |
|---|---|---|---|
Max DrawdownLargest peak-to-trough decline | -5.35% | -55.18% | +49.83% |
Max Drawdown (1Y)Largest decline over 1 year | -0.72% | -8.90% | +8.18% |
Max Drawdown (3Y)Largest decline over 3 years | -0.92% | -18.75% | +17.83% |
Max Drawdown (5Y)Largest decline over 5 years | -5.35% | -24.50% | +19.15% |
Max Drawdown (10Y)Largest decline over 10 years | -5.35% | -33.79% | +28.44% |
Current DrawdownCurrent decline from peak | -0.39% | -2.94% | +2.55% |
Average DrawdownAverage peak-to-trough decline | -1.01% | -10.01% | +9.00% |
Ulcer IndexDepth and duration of drawdowns from previous peaks | 0.18% | 1.91% | -1.73% |
Volatility
VTSPX vs. VIIIX - Volatility Comparison
The current volatility for Vanguard Short-Term Inflation-Protected Securities Index Fund Institutional Shares (VTSPX) is 0.61%, while Vanguard Institutional Index Fund Institutional Plus Shares (VIIIX) has a volatility of 3.81%. This indicates that VTSPX experiences smaller price fluctuations and is considered to be less risky than VIIIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.
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Volatility by Period
| VTSPX | VIIIX | Difference | |
|---|---|---|---|
Volatility (1M)Calculated over the trailing 1-month period | 0.61% | 3.81% | -3.20% |
Volatility (6M)Calculated over the trailing 6-month period | 1.16% | 9.41% | -8.25% |
Volatility (1Y)Calculated over the trailing 1-year period | 1.55% | 12.19% | -10.64% |
Volatility (5Y)Calculated over the trailing 5-year period, annualized | 2.67% | 16.93% | -14.26% |
Volatility (10Y)Calculated over the trailing 10-year period, annualized | 2.23% | 18.08% | -15.85% |
VTSPX vs. VIIIX - Expense Ratio Comparison
VTSPX has a 0.04% expense ratio, which is higher than VIIIX'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
VTSPX vs. VIIIX - Dividend Comparison
VTSPX's dividend yield for the trailing twelve months is around 3.60%, more than VIIIX's 2.48% yield.
| Position | TTM | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
VIIIX Vanguard Institutional Index Fund Institutional Plus Shares | 2.48% | 2.11% | 3.66% | 2.66% | 3.39% | 4.79% | 3.07% | 2.86% | 2.45% | 1.84% | 2.38% | 2.47% |
VTSPX Vanguard Short-Term Inflation-Protected Securities Index Fund Institutional Shares | 3.60% | 3.81% | 2.70% | 2.86% | 6.84% | 4.69% | 1.21% | 1.96% | 2.47% | 1.52% | 0.80% | 0.00% |
Frequently Asked Questions
VTSPX and VIIIX have a correlation of -0.02, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.
VIIIX has higher volatility (3.81%) compared to VTSPX (0.61%). In terms of maximum drawdown, VTSPX dropped -5.35% vs VIIIX's -55.18%.
VTSPX currently has the higher Sharpe Ratio (2.85 vs 2.13), 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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