V-Lab
JSE Securities South African Volatility Index Spline-GARCH Volatility Analysis
Volatility prediction for Friday, August 7th, 2026
1 Day
106.76%
increased by 10.52%
1 Week
95.02%
decreased by 1.22%
1 Month
72.86%
decreased by 23.38%
Analysis last updated: Friday, August 7, 2026 at 08:37 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
Spline-GARCH Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.6624 | 5.00*** |
α ARCH Response to squared shocks | 0.1212 | 4.40*** |
β GARCH Volatility persistence | 0.7147 | 12.49*** |
Spline Coefficients
K=6
| γ1 | -0.1495 | -1.99** |
| γ2 | 0.2837 | 2.47** |
| γ3 | -0.2872 | -2.75*** |
| γ4 | 0.3400 | 3.13*** |
| γ5 | -0.3729 | -3.81*** |
| γ6 | 0.3344 | 3.07*** |
Persistence:
0.836
Half-life:
4 days
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