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V-Lab

Vanguard S&P 500 Index ETF Zero Slope Spline-GARCH Volatility Analysis

Volatility prediction for Monday, July 27th, 2026

1 Day

12.78%

decreased by 0.78%

1 Week

12.94%

decreased by 0.62%

1 Month

13.39%

decreased by 0.17%

Analysis last updated: Saturday, July 25, 2026 at 09:14 AM UTC

Date Range:

from

to

6M ·

1Y ·

2Y ·

5Y ·

10Y ·

All

graph of Vanguard S&P 500 Index ETF S0GARCH

News Impact Curve

How returns affect tomorrow's volatility

Volatility Forecast

How volatility evolves over time

Parameter Estimates

Nov 8, 2012 to Jul 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 12 trading days.

τ

Zero Slope Spline-GARCH Model

Tap to view equation

ParameterValuet-statistic
ω

const

Unconditional variance weight

0.8617
10.72***
α

ARCH

Response to squared shocks

0.1202
7.38***
β

GARCH

Volatility persistence

0.8259
40.96***
γi Spline Coefficients
K=1
γ1-0.0005
-0.48

Persistence:

0.946

Half-life:

12 days