V-Lab
S&P 500 Equal Weight Index (EWI) MEM Volatility Analysis
Volatility prediction for Monday, September 14th, 2026
1 Day
9.39%
decreased by 0.78%
1 Week
9.95%
decreased by 0.22%
1 Month
11.72%
increased by 1.55%
Analysis last updated: Saturday, September 12, 2026 at 12:53 AM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Apr 25, 2003 to Sep 11, 2026Model Insight
Volatility shocks decay with a half-life of 33 trading days, meaning a shock loses half its impact after approximately 33 days.
μ
MEM Model
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Shock decay: Shocks decay with a 33-day half-life
| Param | Value | t-stat |
|---|---|---|
| ωconst | 0.0296 | 2.97*** |
| αARCH | 0.2476 | 13.71*** |
| βGARCH | 0.7314 | 51.03*** |
0.979
Persistence33d
Half-lifeμ
MEM Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0296 | 2.97*** |
α ARCH Response to squared shocks | 0.2476 | 13.71*** |
β GARCH Volatility persistence | 0.7314 | 51.03*** |
Persistence:
0.979
Half-life:
33 days
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