V-Lab
JSE Securities South African Volatility Index GJR-GARCH Volatility Analysis
Volatility prediction for Thursday, September 24th, 2026
1 Day
58.38%
increased by 4.01%
1 Week
59.06%
increased by 4.69%
1 Month
60.91%
increased by 6.54%
Analysis last updated: Friday, September 25, 2026 at 08:56 PM UTC
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News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Feb 1, 2007 to Sep 23, 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
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Shock decay: Shocks decay with a 12-day half-life
| Param | Value | t-stat |
|---|---|---|
| ωconst | 0.9552 | 4.43*** |
| αARCH | 0.1299 | 3.23*** |
| βGARCH | 0.8299 | 32.16*** |
| γleverage | -0.0360 | -0.48 |
0.942
Persistence12d
Half-lifeσ
GJR-GARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.9552 | 4.43*** |
α ARCH Response to squared shocks | 0.1299 | 3.23*** |
β GARCH Volatility persistence | 0.8299 | 32.16*** |
γ leverage Additional response to negative shocks | -0.0360 | -0.48 |
Persistence:
0.942
Half-life:
12 days
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