VIIIX vs. PLFIX
VIIIX (Vanguard Institutional Index Fund Institutional Plus Shares) and PLFIX (Principal Large Cap S&P 500 Index Fund Institutional) are both S&P 500 funds tracking the S&P 500 Index, from Vanguard and Principal respectively. Both are passively managed. Over the past 10 years, VIIIX returned 15.65%/yr vs 15.55%/yr for PLFIX. With a 0.99 correlation, they move nearly in lockstep. VIIIX charges 0.02%/yr vs 0.11%/yr for PLFIX.
Performance
VIIIX vs. PLFIX - Performance Comparison
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Returns By Period
The year-to-date returns for both stocks are quite close, with VIIIX having a 10.88% return and PLFIX slightly lower at 10.84%. Both investments have delivered pretty close results over the past 10 years, with VIIIX having a 15.65% annualized return and PLFIX not far behind at 15.55%.
VIIIX
- 1D
- -0.74%
- 1M
- 4.17%
- YTD
- 10.88%
- 6M
- 10.80%
- 1Y
- 28.02%
- 3Y*
- 22.87%
- 5Y*
- 14.05%
- 10Y*
- 15.65%
PLFIX
- 1D
- -0.75%
- 1M
- 4.15%
- YTD
- 10.84%
- 6M
- 10.78%
- 1Y
- 27.92%
- 3Y*
- 22.91%
- 5Y*
- 14.07%
- 10Y*
- 15.55%
VIIIX vs. PLFIX - Yearly Performance Comparison
| 2026 (YTD) | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | |
|---|---|---|---|---|---|---|---|---|---|---|
VIIIX Vanguard Institutional Index Fund Institutional Plus Shares | 10.88% | 17.87% | 26.29% | 25.79% | -18.14% | 28.69% | 18.41% | 31.48% | -4.41% | 21.82% |
PLFIX Principal Large Cap S&P 500 Index Fund Institutional | 10.84% | 17.77% | 26.77% | 26.00% | -18.21% | 28.25% | 18.11% | 31.35% | -4.66% | 21.65% |
Correlation
The correlation between VIIIX and PLFIX is 1.00 - these two move nearly in lockstep. At this level, holding both provides almost no diversification benefit. If you already own one, adding the other does little to reduce portfolio risk.
| Correlation | |
|---|---|
Correlation (1Y) Calculated over the trailing 1-year period | 1.00 |
Correlation (3Y) Calculated over the trailing 3-year period | 0.99 |
Correlation (5Y) Calculated over the trailing 5-year period | 0.99 |
Correlation (10Y) Calculated over the trailing 10-year period | 0.99 |
Correlation (All Time) Calculated using the full available price history since Mar 1, 2001 | 0.99 |
The correlation between VIIIX and PLFIX has been stable across timeframes, ranging from 0.99 to 1.00 - a consistent structural relationship.
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Return for Risk
VIIIX vs. PLFIX — Risk / Return Rank
VIIIX
PLFIX
VIIIX vs. PLFIX - Risk-Adjusted Trends Comparison
This table presents a comparison of risk-adjusted performance metrics for Vanguard Institutional Index Fund Institutional Plus Shares (VIIIX) and Principal Large Cap S&P 500 Index Fund Institutional (PLFIX). 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.
| VIIIX | PLFIX | Difference | |
|---|---|---|---|
| Sharpe ratioReturn per unit of total volatility | 0.00 | ||
| Sortino ratioReturn per unit of downside risk | 0.00 | ||
| Omega ratioGain probability vs. loss probability | 1.43 | 1.43 | 0.00 |
| Calmar ratioReturn relative to maximum drawdown | 3.17 | 3.15 | +0.01 |
| Martin ratioReturn relative to average drawdown | 14.79 | 14.74 | +0.05 |
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
| VIIIX | PLFIX | Difference | |
|---|---|---|---|
Sharpe Ratio (1Y)Calculated over the trailing 1-year period | 2.37 | 2.37 | 0.00 |
Sharpe Ratio (5Y)Calculated over the trailing 5-year period | 0.84 | 0.84 | 0.00 |
Sharpe Ratio (10Y)Calculated over the trailing 10-year period | 0.87 | 0.89 | -0.02 |
Sharpe Ratio (All Time)Calculated using the full available price history | 0.49 | 0.49 | +0.01 |
Drawdowns
VIIIX vs. PLFIX - Drawdown Comparison
The maximum VIIIX drawdown since its inception was -55.18%, roughly equal to the maximum PLFIX drawdown of -55.28%. Use the drawdown chart below to compare losses from any high point for VIIIX and PLFIX.
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Drawdown Indicators
| VIIIX | PLFIX | Difference | |
|---|---|---|---|
Max DrawdownLargest peak-to-trough decline | -55.18% | -55.28% | +0.10% |
Max Drawdown (1Y)Largest decline over 1 year | -8.90% | -8.90% | 0.00% |
Max Drawdown (3Y)Largest decline over 3 years | -18.75% | -18.77% | +0.02% |
Max Drawdown (5Y)Largest decline over 5 years | -24.50% | -24.58% | +0.08% |
Max Drawdown (10Y)Largest decline over 10 years | -33.79% | -33.77% | -0.02% |
Current DrawdownCurrent decline from peak | -0.74% | -0.75% | +0.01% |
Average DrawdownAverage peak-to-trough decline | -10.02% | -8.86% | -1.16% |
Ulcer IndexDepth and duration of drawdowns from previous peaks | 1.90% | 1.90% | 0.00% |
Volatility
VIIIX vs. PLFIX - Volatility Comparison
Vanguard Institutional Index Fund Institutional Plus Shares (VIIIX) and Principal Large Cap S&P 500 Index Fund Institutional (PLFIX) have volatilities of 2.93% and 2.92%, respectively, indicating that both stocks experience similar levels of price fluctuations. This suggests that the risk associated with both stocks, as measured by volatility, is nearly the same. The chart below showcases a comparison of their rolling one-month volatility.
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Volatility by Period
| VIIIX | PLFIX | Difference | |
|---|---|---|---|
Volatility (1M)Calculated over the trailing 1-month period | 2.93% | 2.92% | +0.01% |
Volatility (6M)Calculated over the trailing 6-month period | 8.99% | 8.98% | +0.01% |
Volatility (1Y)Calculated over the trailing 1-year period | 11.88% | 11.87% | +0.01% |
Volatility (5Y)Calculated over the trailing 5-year period, annualized | 16.89% | 16.91% | -0.02% |
Volatility (10Y)Calculated over the trailing 10-year period, annualized | 18.06% | 17.51% | +0.55% |
VIIIX vs. PLFIX - Expense Ratio Comparison
VIIIX has a 0.02% expense ratio, which is lower than PLFIX's 0.11% expense ratio. Despite the difference, both funds are considered low-cost compared to the broader market, where average expense ratios usually range from 0.3% to 0.9%.
Dividends
VIIIX vs. PLFIX - Dividend Comparison
VIIIX's dividend yield for the trailing twelve months is around 2.43%, less than PLFIX's 2.66% yield.
| Position | TTM | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
PLFIX Principal Large Cap S&P 500 Index Fund Institutional | 2.66% | 2.95% | 4.28% | 4.13% | 2.96% | 13.60% | 7.57% | 3.83% | 7.52% | 7.01% | 3.23% | 2.69% |
VIIIX Vanguard Institutional Index Fund Institutional Plus Shares | 2.43% | 2.11% | 3.66% | 2.66% | 3.39% | 4.79% | 3.07% | 2.86% | 2.45% | 1.84% | 2.38% | 2.47% |
Frequently Asked Questions
With a correlation of 1.00, VIIIX and PLFIX move almost identically. Holding both adds very little diversification - you're essentially doubling your position in the same market segment. Choosing one is usually more capital-efficient.
VIIIX has higher volatility (2.93%) compared to PLFIX (2.92%). In terms of maximum drawdown, VIIIX dropped -55.18% vs PLFIX's -55.28%.
VIIIX currently has the higher Sharpe Ratio (2.37 vs 2.37), 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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