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V-Lab

Russell Midcap Index Spline-GARCH Volatility Analysis

Volatility prediction for Friday, September 25th, 2026

1 Day

11.77%

decreased by 0.43%

1 Week

12.21%

increased by 0.01%

1 Month

13.57%

increased by 1.37%

Analysis last updated: Friday, September 25, 2026 at 08:56 PM UTC

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graph of Russell Midcap Index SGARCH

News Impact Curve

How returns affect tomorrow's volatility

Volatility Forecast

How volatility evolves over time

Parameter Estimates

Mar 1, 2004 to Sep 24, 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

Spline-GARCH Model

Tap to view equation

Time-varying baseline: volatility reverts to a slowly-shifting spline trend
ParamValuet-stat
ωconst0.5040
5.65***
αARCH0.1181
9.51***
βGARCH0.8532
61.93***
∑γi Spline Coefficients
K=3
γ1-0.0464
-3.85***
γ20.0686
3.73***
γ3-0.0350
-2.15**

0.971

Persistence

24d

Half-life
τ

Spline-GARCH Model

Tap to view equation

ParameterValuet-statistic
ω

const

Unconditional variance weight

0.5040
5.65***
α

ARCH

Response to squared shocks

0.1181
9.51***
β

GARCH

Volatility persistence

0.8532
61.93***
∑γi Spline Coefficients
K=3
γ1-0.0464
-3.85***
γ20.0686
3.73***
γ3-0.0350
-2.15**

Persistence:

0.971

Half-life:

24 days