V-Lab
Appian Corp Zero Slope Spline-GARCH Volatility Analysis
Volatility prediction for Tuesday, September 22nd, 2026
1 Day
57.65%
decreased by 0.44%
1 Week
59.33%
increased by 1.24%
1 Month
61.43%
increased by 3.34%
Analysis last updated: Monday, September 21, 2026 at 09:19 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
May 25, 2017 to Sep 18, 2026Model 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 3 trading days.
τ
Zero Slope Spline-GARCH Model
Tap to view equation
Time-varying baseline: volatility reverts to a slowly-shifting spline trend
| Param | Value | t-stat |
|---|---|---|
| ωconst | 1.1535 | 6.91*** |
| αARCH | 0.1277 | 3.17*** |
| βGARCH | 0.6644 | 7.63*** |
Spline Coefficients
K=4
| γ1 | 0.2800 | 2.85*** |
| γ2 | -0.5165 | -3.49*** |
| γ3 | 0.3796 | 3.37*** |
| γ4 | -0.1749 | -1.99** |
0.792
Persistence3d
Half-lifeτ
Zero Slope Spline-GARCH Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 1.1535 | 6.91*** |
α ARCH Response to squared shocks | 0.1277 | 3.17*** |
β GARCH Volatility persistence | 0.6644 | 7.63*** |
Spline Coefficients
K=4
| γ1 | 0.2800 | 2.85*** |
| γ2 | -0.5165 | -3.49*** |
| γ3 | 0.3796 | 3.37*** |
| γ4 | -0.1749 | -1.99** |
Persistence:
0.792
Half-life:
3 days
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