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S&P 500 Index Asy. Power MEM Volatility Analysis

Volatility prediction for Friday, October 23rd, 2026

1 Day

12.58%

increased by 0.72%

1 Week

12.26%

increased by 0.40%

1 Month

11.38%

decreased by 0.48%

Analysis last updated: Friday, October 23, 2026 at 12:04 AM UTC

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Date Range:

from

10/22/2024

to

10/22/2026

6M ·

1Y ·

2Y ·

5Y ·

10Y ·

All

graph of S&P 500 Index APMEM

News Impact Curve

How returns affect tomorrow's volatility

Volatility Forecast

How volatility evolves over time

Parameter Estimates

Jan 1, 1990 to Oct 16, 2026

Model Insight

This asset exhibits a strong leverage effect: negative returns increase next-day volatility 101% more than equivalent positive returns. The volatility power δ = 1.04 sits below 2, so large shocks influence volatility less than quadratically, a more outlier-robust response than standard GARCH.

μ

APMEM Model

Tap to view equation

Leverage: Negative returns increase volatility 101% more than positive returnsδ = 1.04 · sub-quadratic power
ParamValuet-stat
ωconst0.0328
9.81***
αARCH0.1891
14.63***
βGARCH0.7927
60.88***
γleverage0.3232
8.23***
δpower1.0400
8.74***

0.944

Persistence

12d

Half-life
μ

APMEM Model

Tap to view equation

ParameterValuet-statistic
ω

const

Unconditional variance weight

0.0328
9.81***
α

ARCH

Response to squared shocks

0.1891
14.63***
β

GARCH

Volatility persistence

0.7927
60.88***
γ

leverage

Additional response to negative shocks

0.3232
8.23***
δ

power

Transformation power

1.0400
8.74***

Persistence:

0.944

Half-life:

12 days