SPX vs VIX Divergence Signal

Overview

This pillar analyzes the critical relationship between the S&P 500 (SPX) and the CBOE Volatility Index (VIX). It identifies rare divergence events, where the market's direction and its fear gauge move in tandem, often signaling an impending reversal or increased instability.

What It Does

The pillar continuously tracks the daily percentage change of both the SPX and the VIX. It flags instances where both indices move in the same direction, a break from their typical inverse correlation. This non-confirmation is quantified to signal potential market fragility or overconfidence.

Why It Matters

This divergence is a powerful leading indicator of market sentiment shifts. A 'fearful rally' (SPX up, VIX up) suggests weak conviction, while a 'complacent drop' (SPX down, VIX down) indicates a lack of hedging, making the market vulnerable to shocks.

How It Works

First, the pillar ingests daily closing prices for the SPX and VIX. It then calculates the daily percentage change for each index. Finally, it applies a logical filter to identify trading days where both changes are positive or both are negative, triggering a divergence signal.

Methodology

The core calculation is based on the 1-day percentage change of SPX and VIX. A divergence event is flagged when the sign of the SPX's daily change matches the sign of the VIX's daily change. For deeper analysis, it also calculates a rolling 20-day Pearson correlation coefficient between the two indices; a coefficient moving towards zero or positive values indicates a structural breakdown in the normal relationship.

Edge & Advantage

It provides an early warning of sentiment shifts not apparent from price action alone, allowing traders to anticipate volatility before it spikes.

Key Indicators

• Divergence Alert

  high

  A binary signal (On/Off) that triggers when SPX and VIX move in the same direction on a given day.

• Spot-Vol Correlation Coefficient

  medium

  A rolling 20-day correlation between SPX and VIX returns. Values approaching zero or turning positive are highly anomalous.

• Beta-Adjusted VIX Move

  low

  Measures the VIX's movement relative to its expected move based on the SPX's change, highlighting outsized fear or complacency.

Data Sources

• CBOE Global Markets

  Provides the official daily and historical data for the VIX Index.

• S&P Dow Jones Indices

  Provides the official daily and historical data for the S&P 500 Index.

Example Questions This Pillar Answers

• → Will the S&P 500 close down more than 2% in the next week?
• → Will the VIX index close above 30 by the end of the month?
• → Will the current stock market rally sustain for another 5 trading days?

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