V-Lab
S&P Total Market Index Zero Slope Spline-GARCH Volatility Analysis
Volatility prediction for Wednesday, August 26th, 2026
1 Day
11.99%
decreased by 0.38%
1 Week
12.61%
increased by 0.24%
1 Month
14.42%
increased by 2.05%
Analysis last updated: Tuesday, August 25, 2026 at 11:06 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Mar 30, 2006 to Aug 21, 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 20 trading days.
τ
Zero Slope Spline-GARCH Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.8905 | 5.83*** |
α ARCH Response to squared shocks | 0.1305 | 8.83*** |
β GARCH Volatility persistence | 0.8350 | 49.39*** |
Spline Coefficients
K=3
| γ1 | -0.0275 | -2.31** |
| γ2 | 0.0500 | 2.79*** |
| γ3 | -0.0312 | -3.12*** |
Persistence:
0.966
Half-life:
20 days
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