CBOE S&P 500 9-Day Volatility Index Spline-GARCH Volatility Analysis
Volatility prediction for Monday, November 9th, 2026
1 Day
427.74%
decreased by 90.90%
1 Week
361.68%
decreased by 156.96%
1 Month
293.14%
decreased by 225.50%
Analysis last updated: Monday, November 9, 2026 at 12:35 PM UTC
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News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jan 3, 2011 to Nov 6, 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 2 trading days.
τ
Spline-GARCH Model
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Time-varying baseline: volatility reverts to a slowly-shifting spline trend
| Param | Value | t-stat |
|---|---|---|
| ωconst | 0.9163 | 9.84*** |
| αARCH | 0.1305 | 3.98*** |
| βGARCH | 0.5606 | 6.85*** |
Spline Coefficients
K=3
| γ1 | 0.0187 | 1.38 |
| γ2 | -0.0476 | -2.26** |
| γ3 | 0.0776 | 3.80*** |
0.691
Persistence2d
Half-lifeτ
Spline-GARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.9163 | 9.84*** |
α ARCH Response to squared shocks | 0.1305 | 3.98*** |
β GARCH Volatility persistence | 0.5606 | 6.85*** |
Spline Coefficients
K=3
| γ1 | 0.0187 | 1.38 |
| γ2 | -0.0476 | -2.26** |
| γ3 | 0.0776 | 3.80*** |
Persistence:
0.691
Half-life:
2 days
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