S&P MidCap 400 Index MEM Volatility Analysis
Volatility prediction for Tuesday, October 27th, 2026
1 Day
12.71%
decreased by 0.26%
1 Week
13.00%
increased by 0.03%
1 Month
14.02%
increased by 1.05%
Analysis last updated: Monday, October 26, 2026 at 11:01 PM UTC
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News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jun 3, 1991 to Oct 23, 2026Model Insight
Volatility shocks decay with a half-life of 47 trading days, meaning a shock loses half its impact after approximately 47 days.
μ
MEM Model
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Shock decay: Shocks decay with a 47-day half-life
| Param | Value | t-stat |
|---|---|---|
| ωconst | 0.0245 | 3.88*** |
| αARCH | 0.1990 | 15.00*** |
| βGARCH | 0.7864 | 65.71*** |
0.985
Persistence47d
Half-lifeμ
MEM Model
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| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0245 | 3.88*** |
α ARCH Response to squared shocks | 0.1990 | 15.00*** |
β GARCH Volatility persistence | 0.7864 | 65.71*** |
Persistence:
0.985
Half-life:
47 days
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