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V-Lab

Russell Midcap Index Zero Slope Spline-GARCH Volatility Analysis

Volatility prediction for Friday, September 18th, 2026

1 Day

13.45%

increased by 0.13%

1 Week

13.87%

increased by 0.55%

1 Month

15.20%

increased by 1.88%

Analysis last updated: Friday, September 18, 2026 at 09:54 PM UTC

Date Range:

from

to

6M ·

1Y ·

2Y ·

5Y ·

10Y ·

All

graph of Russell Midcap Index S0GARCH

News Impact Curve

How returns affect tomorrow's volatility

Volatility Forecast

How volatility evolves over time

Parameter Estimates

Mar 1, 2004 to Sep 10, 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 24 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
ωconst0.5172
5.76***
αARCH0.1185
9.54***
βGARCH0.8533
62.24***
∑γi Spline Coefficients
K=3
γ1-0.0440
-3.86***
γ20.0635
3.90***
γ3-0.0259
-3.37***

0.972

Persistence

24d

Half-life
τ

Zero Slope Spline-GARCH Model

Tap to view equation

ParameterValuet-statistic
ω

const

Unconditional variance weight

0.5172
5.76***
α

ARCH

Response to squared shocks

0.1185
9.54***
β

GARCH

Volatility persistence

0.8533
62.24***
∑γi Spline Coefficients
K=3
γ1-0.0440
-3.86***
γ20.0635
3.90***
γ3-0.0259
-3.37***

Persistence:

0.972

Half-life:

24 days