V-Lab
JSE Securities South African Volatility Index AGARCH Volatility Analysis
Volatility prediction for Friday, August 7th, 2026
1 Day
104.79%
decreased by 9.34%
1 Week
100.25%
decreased by 13.88%
1 Month
87.20%
decreased by 26.93%
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
The news-impact curve is shifted (γ = -1.49) so that positive returns raise next-day volatility more than negative returns of the same size. Volatility rises more after gains than after losses, the reverse of the usual leverage effect and rare among risky assets.
σ
AGARCH Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.7159 | 13.17*** |
α ARCH Response to squared shocks | 0.1040 | 20.24*** |
β GARCH Volatility persistence | 0.8291 | 129.50*** |
γ leverage Additional response to negative shocks | -1.4891 | -10.25*** |
Persistence:
0.933
Half-life:
10 days
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