V-Lab
Vanguard S&P 500 Index ETF Zero Slope Spline-GARCH Volatility Analysis
Volatility prediction for Monday, July 27th, 2026
1 Day
12.78%
decreased by 0.78%
1 Week
12.94%
decreased by 0.62%
1 Month
13.39%
decreased by 0.17%
Analysis last updated: Saturday, July 25, 2026 at 09:14 AM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Nov 8, 2012 to Jul 24, 2026Model Insight
This model fits a time-varying baseline (a spline), so volatility mean-reverts toward a slowly-shifting long-run level rather than a constant. Short-run deviations decay with a half-life of 12 trading days.
τ
Zero Slope Spline-GARCH Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.8617 | 10.72*** |
α ARCH Response to squared shocks | 0.1202 | 7.38*** |
β GARCH Volatility persistence | 0.8259 | 40.96*** |
Spline Coefficients
K=1
| γ1 | -0.0005 | -0.48 |
Persistence:
0.946
Half-life:
12 days
Other Vanguard S&P 500 Index ETF Analyses
Other Zero Slope Spline-GARCH Analyses on ETFs