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V-Lab
V-Lab

S&P MidCap 400 Index Zero Slope Spline-GARCH Volatility Analysis

Volatility prediction for Thursday, September 10th, 2026

1 Day

13.96%

increased by 0.60%

1 Week

14.25%

increased by 0.89%

1 Month

15.22%

increased by 1.86%

Analysis last updated: Wednesday, September 9, 2026 at 11:02 PM UTC

Date Range:

from

to

6M ·

1Y ·

2Y ·

5Y ·

10Y ·

All

graph of S&P MidCap 400 Index S0GARCH

News Impact Curve

How returns affect tomorrow's volatility

Volatility Forecast

How volatility evolves over time

Parameter Estimates

Jan 1, 1990 to Sep 8, 2026

Model Insight

This model fits a time-varying baseline (a spline), so volatility mean-reverts toward a slowly-shifting long-run level rather than a constant. Short-run deviations decay with a half-life of 35 trading days.

τ

Zero Slope Spline-GARCH Model

Tap to view equation

Time-varying baseline: volatility reverts to a slowly-shifting spline trend
ParamValuet-stat
ωconst0.7803
9.72***
αARCH0.1022
10.91***
βGARCH0.8780
89.82***
γi Spline Coefficients
K=1
γ1-0.0003
-2.30**

0.980

Persistence

35d

Half-life
τ

Zero Slope Spline-GARCH Model

Tap to view equation

ParameterValuet-statistic
ω

const

Unconditional variance weight

0.7803
9.72***
α

ARCH

Response to squared shocks

0.1022
10.91***
β

GARCH

Volatility persistence

0.8780
89.82***
γi Spline Coefficients
K=1
γ1-0.0003
-2.30**

Persistence:

0.980

Half-life:

35 days