Skip to main content
V-Lab

JSE Securities South African Volatility Index GJR-GARCH Volatility Analysis

Volatility prediction for Friday, July 24th, 2026

1 Day

129.18%

increased by 20.84%

1 Week

122.73%

increased by 14.39%

1 Month

103.69%

decreased by 4.65%

Analysis last updated: Friday, July 24, 2026 at 11:19 PM UTC

Date Range:

from

to

6M ·

1Y ·

2Y ·

5Y ·

10Y ·

All

graph of JSE Securities South African Volatility Index GJR-GARCH

News Impact Curve

How returns affect tomorrow's volatility

Volatility Forecast

How volatility evolves over time

Parameter Estimates

Feb 1, 2007 to Apr 4, 2025

Model Insight

This asset shows a rare inverse leverage effect: positive returns raise next-day volatility 58% more than negative returns. Volatility rises more after gains than after losses, the reverse of the usual leverage effect and uncommon among risky assets.

σ

GJR-GARCH Model

Tap to view equation

ParameterValuet-statistic
ω

const

Unconditional variance weight

0.8976
14.13***
α

ARCH

Response to squared shocks

0.1206
11.67***
β

GARCH

Volatility persistence

0.8360
99.96***
γ

leverage

Additional response to negative shocks

-0.0442
-2.46**

Persistence:

0.934

Half-life:

10 days