WFSPX vs. VIIIX
WFSPX (iShares S&P 500 Index Fund Class K) and VIIIX (Vanguard Institutional Index Fund Institutional Plus Shares) are both S&P 500 funds tracking the S&P 500 Index, from BlackRock and Vanguard respectively. Both are passively managed. Over the past 10 years, WFSPX returned 15.50%/yr vs 15.69%/yr for VIIIX. With a 1.00 correlation, they move nearly in lockstep. WFSPX charges 0.03%/yr vs 0.02%/yr for VIIIX.
Performance
WFSPX vs. VIIIX - Performance Comparison
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Returns By Period
The year-to-date returns for both investments are quite close, with WFSPX having a 8.09% return and VIIIX slightly higher at 8.10%. Both investments have delivered pretty close results over the past 10 years, with WFSPX having a 15.50% annualized return and VIIIX not far ahead at 15.69%.
WFSPX
- 1D
- -0.10%
- 1M
- -2.04%
- YTD
- 8.09%
- 6M
- 6.76%
- 1Y
- 22.17%
- 3Y*
- 20.73%
- 5Y*
- 13.01%
- 10Y*
- 15.50%
VIIIX
- 1D
- -0.10%
- 1M
- -2.04%
- YTD
- 8.10%
- 6M
- 6.77%
- 1Y
- 22.22%
- 3Y*
- 21.18%
- 5Y*
- 13.19%
- 10Y*
- 15.69%
WFSPX vs. VIIIX - Yearly Performance Comparison
| 2026 (YTD) | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | |
|---|---|---|---|---|---|---|---|---|---|---|
WFSPX iShares S&P 500 Index Fund Class K | 8.09% | 17.83% | 24.94% | 26.25% | -18.14% | 28.63% | 18.43% | 31.45% | -4.83% | 21.27% |
VIIIX Vanguard Institutional Index Fund Institutional Plus Shares | 8.10% | 17.87% | 26.29% | 25.79% | -18.14% | 28.69% | 18.41% | 31.48% | -4.41% | 21.82% |
Correlation
The correlation between WFSPX and VIIIX 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 | 1.00 |
Correlation (5Y) Calculated over the trailing 5-year period | 1.00 |
Correlation (10Y) Calculated over the trailing 10-year period | 1.00 |
Correlation (All Time) Calculated using the full available price history since Jul 7, 1997 | 1.00 |
The correlation between WFSPX and VIIIX has been stable across timeframes, ranging from 1.00 to 1.00 - a consistent structural relationship.
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Return for Risk
WFSPX vs. VIIIX — Risk / Return Rank
WFSPX
VIIIX
WFSPX vs. VIIIX - Risk-Adjusted Trends Comparison
This table presents a comparison of risk-adjusted performance metrics for iShares S&P 500 Index Fund Class K (WFSPX) 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.
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.
| WFSPX | VIIIX | Difference | |
|---|---|---|---|
| Sharpe ratioReturn per unit of total volatility | 0.00 | ||
| Sortino ratioReturn per unit of downside risk | -0.01 | ||
| Omega ratioGain probability vs. loss probability | 1.32 | 1.32 | 0.00 |
| Calmar ratioReturn relative to maximum drawdown | 2.50 | 2.51 | -0.01 |
| Martin ratioReturn relative to average drawdown | 11.18 | 11.22 | -0.04 |
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Drawdowns
WFSPX vs. VIIIX - Drawdown Comparison
The maximum WFSPX drawdown since its inception was -58.21%, which is greater than VIIIX's maximum drawdown of -55.18%. Use the drawdown chart below to compare losses from any high point for WFSPX and VIIIX.
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Drawdown Indicators
| WFSPX | VIIIX | Difference | |
|---|---|---|---|
Max DrawdownLargest peak-to-trough decline | -58.21% | -55.18% | -3.03% |
Max Drawdown (1Y)Largest decline over 1 year | -8.90% | -8.90% | 0.00% |
Max Drawdown (3Y)Largest decline over 3 years | -18.74% | -18.75% | +0.01% |
Max Drawdown (5Y)Largest decline over 5 years | -24.51% | -24.50% | -0.01% |
Max Drawdown (10Y)Largest decline over 10 years | -33.74% | -33.79% | +0.05% |
Current DrawdownCurrent decline from peak | -3.22% | -3.22% | 0.00% |
Average DrawdownAverage peak-to-trough decline | -12.75% | -10.00% | -2.75% |
Ulcer IndexDepth and duration of drawdowns from previous peaks | 1.99% | 1.99% | 0.00% |
Volatility
WFSPX vs. VIIIX - Volatility Comparison
iShares S&P 500 Index Fund Class K (WFSPX) and Vanguard Institutional Index Fund Institutional Plus Shares (VIIIX) have volatilities of 4.88% and 4.88%, 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
| WFSPX | VIIIX | Difference | |
|---|---|---|---|
Volatility (1M)Calculated over the trailing 1-month period | 4.88% | 4.88% | 0.00% |
Volatility (6M)Calculated over the trailing 6-month period | 9.89% | 9.90% | -0.01% |
Volatility (1Y)Calculated over the trailing 1-year period | 12.53% | 12.54% | -0.01% |
Volatility (5Y)Calculated over the trailing 5-year period, annualized | 16.98% | 16.99% | -0.01% |
Volatility (10Y)Calculated over the trailing 10-year period, annualized | 18.04% | 18.08% | -0.04% |
WFSPX vs. VIIIX - Expense Ratio Comparison
WFSPX has a 0.03% 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
WFSPX vs. VIIIX - Dividend Comparison
WFSPX's dividend yield for the trailing twelve months is around 1.62%, less than VIIIX's 2.80% yield.
| Position | TTM | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
VIIIX Vanguard Institutional Index Fund Institutional Plus Shares | 2.80% | 2.11% | 3.66% | 2.66% | 3.39% | 4.79% | 3.07% | 2.86% | 2.45% | 1.84% | 2.38% | 2.47% |
WFSPX iShares S&P 500 Index Fund Class K | 1.62% | 1.72% | 1.41% | 1.50% | 2.02% | 1.82% | 1.66% | 1.99% | 2.00% | 1.62% | 2.37% | 2.49% |
Frequently Asked Questions
With a correlation of 1.00, WFSPX and VIIIX 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 (4.88%) compared to WFSPX (4.88%). In terms of maximum drawdown, WFSPX dropped -58.21% vs VIIIX's -55.18%.
VIIIX currently has the higher Sharpe Ratio (1.79 vs 1.78), 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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