V-Lab
JSE Securities South African Volatility Index Zero Slope Spline-GARCH Volatility Analysis
Volatility prediction for Friday, July 24th, 2026
1 Day
119.20%
increased by 22.12%
1 Week
107.62%
increased by 10.54%
1 Month
86.10%
decreased by 10.98%
Analysis last updated: Friday, July 24, 2026 at 11:19 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Feb 1, 2007 to Apr 4, 2025Model 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 4 trading days.
τ
Zero Slope Spline-GARCH Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.6657 | 4.99*** |
α ARCH Response to squared shocks | 0.1214 | 4.35*** |
β GARCH Volatility persistence | 0.7166 | 12.65*** |
Spline Coefficients
K=6
| γ1 | -0.1454 | -1.93* |
| γ2 | 0.2758 | 2.40** |
| γ3 | -0.2770 | -2.65*** |
| γ4 | 0.3195 | 3.00*** |
| γ5 | -0.3248 | -3.71*** |
| γ6 | 0.2030 | 3.52*** |
Persistence:
0.838
Half-life:
4 days
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