S&P MidCap 400 Index GARCH Volatility Analysis
Volatility prediction for Monday, October 19th, 2026
1 Day
14.01%
increased by 0.13%
1 Week
14.19%
increased by 0.31%
1 Month
14.81%
increased by 0.93%
Analysis last updated: Friday, October 16, 2026 at 11:50 PM UTC
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News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jan 1, 1990 to Oct 16, 2026Model Insight
Volatility shocks decay with a half-life of 41 trading days, meaning a shock loses half its impact after approximately 41 days.
σ
GARCH Model
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Shock decay: Shocks decay with a 41-day half-life
| Param | Value | t-stat |
|---|---|---|
| ωconst | 0.0232 | 6.39*** |
| αARCH | 0.1008 | 10.99*** |
| βGARCH | 0.8826 | 93.73*** |
0.983
Persistence41d
Half-lifeσ
GARCH Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0232 | 6.39*** |
α ARCH Response to squared shocks | 0.1008 | 10.99*** |
β GARCH Volatility persistence | 0.8826 | 93.73*** |
Persistence:
0.983
Half-life:
41 days
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