V-Lab
JSE Securities South African Volatility Index GJR-GARCH Volatility Analysis
Volatility prediction for Friday, September 4th, 2026
1 Day
86.05%
decreased by 6.71%
1 Week
83.99%
decreased by 8.77%
1 Month
77.96%
decreased by 14.80%
Analysis last updated: Friday, September 4, 2026 at 11:27 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Feb 1, 2007 to Aug 27, 2026Model Insight
Volatility shocks decay with a half-life of 12 trading days, meaning a shock loses half its impact after approximately 12 days.
σ
GJR-GARCH Model
Tap to view equation
Shock decay: Shocks decay with a 12-day half-life
| Param | Value | t-stat |
|---|---|---|
| ωconst | 0.9427 | 4.36*** |
| αARCH | 0.1293 | 3.22*** |
| βGARCH | 0.8314 | 32.09*** |
| γleverage | -0.0357 | -0.48 |
0.943
Persistence12d
Half-lifeσ
GJR-GARCH Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.9427 | 4.36*** |
α ARCH Response to squared shocks | 0.1293 | 3.22*** |
β GARCH Volatility persistence | 0.8314 | 32.09*** |
γ leverage Additional response to negative shocks | -0.0357 | -0.48 |
Persistence:
0.943
Half-life:
12 days
Other JSE Securities South African Volatility Index Analyses
Other GJR-GARCH Analyses on Volatility Indices