V-Lab
AT&T Inc GARCH Volatility Analysis
Volatility prediction for Friday, September 11th, 2026
1 Day
23.55%
increased by 0.11%
1 Week
23.58%
increased by 0.14%
1 Month
23.72%
increased by 0.28%
Analysis last updated: Thursday, September 10, 2026 at 10:02 PM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jan 2, 1990 to Sep 4, 2026Model Insight
With persistence 0.991, volatility shocks have a half-life of 74 trading days (~0.3 years), close to a unit root, so long-run forecasts are highly sensitive to this estimate.
σ
GARCH Model
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High persistence: persistence 0.991, shock half-life ~74 days
| Param | Value | t-stat |
|---|---|---|
| ωconst | 0.0240 | 5.02*** |
| αARCH | 0.0529 | 8.53*** |
| βGARCH | 0.9377 | 140.63*** |
0.991
Persistence74d
Half-lifeσ
GARCH Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.0240 | 5.02*** |
α ARCH Response to squared shocks | 0.0529 | 8.53*** |
β GARCH Volatility persistence | 0.9377 | 140.63*** |
Persistence:
0.991
Half-life:
74 days
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