Gamma Exposure (GEX): Dealer Hedging and Market Structure

Gamma exposure quantifies how options market makers must hedge their positions as the underlying moves. Understanding GEX provides insight into conditions where dealer hedging may amplify or dampen price moves.

This content is for educational purposes only and does not constitute investment advice. Options trading involves substantial risk. Past patterns do not guarantee future results.

View Live GEX Heatmap

Real-time gamma exposure visualization across strikes and expirations

What Is Gamma Exposure?

Gamma exposure (GEX) measures the aggregate gamma held by options dealers across all strikes and expirations. When dealers are net long gamma, they buy dips and sell rallies to stay delta-neutral, dampening volatility. When net short gamma, they must sell into declines and buy into rallies, amplifying moves.

This mechanical hedging behavior is associated with observable patterns in price action that traders may study as part of their own research. GEX analysis is particularly useful for understanding why certain price levels can act as magnets or barriers.

Dealer Positioning Mechanics

Market makers take the opposite side of customer trades. When retail buys calls, dealers sell calls and must buy shares to hedge. As the underlying moves, dealers continuously adjust their hedges based on their gamma exposure.

How GEX Affects Price Movement

The sign and magnitude of aggregate GEX determines market behavior:

Positive GEX (Long Gamma): Dealers hedge against the move. Price tends to mean-revert. Volatility compresses. Common above major put strikes.
Negative GEX (Short Gamma): Dealers hedge with the move. Price trends continue. Volatility expands. Common during selloffs when puts are in-the-money.
Gamma Flip: The price level where aggregate GEX changes sign. Crossing this level shifts market dynamics dramatically.

GEX = Gamma × Open Interest × 100 × Spot Price²

Key GEX Levels for Traders

Specific GEX concentrations create actionable trading levels:

High GEX Strike: Acts as a price magnet. Dealers continuously hedge toward this level, creating pinning behavior especially near expiration.
Zero GEX (Gamma Flip): Transition zone between supportive and volatile regimes. Key inflection point for trend identification.
Put Wall: Strike with highest put-side GEX. Often monitored as potential support, as dealers may buy the underlying when puts go in-the-money.
Call Wall: Strike with highest call-side GEX. Commonly interpreted as potential resistance, as dealers may sell into rallies.

SPX Gamma Exposure Today

Current GEX levels, gamma flip, and dealer positioning for S&P 500

Intraday GEX Dynamics

GEX is not static. Throughout the trading day, gamma exposure shifts due to:

New option trades: Large sweeps or blocks change aggregate positioning
Price movement: As spot moves, different strikes become relevant
Time decay: Gamma increases for at-the-money options as expiration approaches
Volatility changes: IV shifts affect gamma magnitude

Real-time GEX monitoring is essential for day traders, particularly around 0DTE expirations where gamma effects are most pronounced.

Using GEX in Your Trading

Practical applications of gamma exposure analysis:

Analyze potential support/resistance: High GEX strikes may create hedging zones that traders monitor
Monitor volatility conditions: Negative GEX environments have historically been associated with expanded volatility
Consider timing context: Some traders monitor gamma flip levels as part of their analytical framework
Understand expiration dynamics: 0DTE GEX can significantly influence intraday behavior

TeploMap Real-Time GEX Analysis

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Gamma Exposure FAQ

How do dealers hedge gamma exposure?

Dealers hedge by buying or selling the underlying to stay delta-neutral. Long gamma means they buy dips and sell rallies, so their hedge works against the move. Short gamma forces them to sell into declines and buy into rallies, so the hedge works with the move. The direction of hedging flow depends entirely on whether aggregate positioning is net long or short gamma at current price.

What happens when aggregate GEX turns negative?

Dealers become forced sellers into weakness and forced buyers into strength. This feedback loop amplifies directional moves rather than dampening them. Volatility expands, trends extend further than expected, and mean reversion breaks down. Negative GEX environments typically see larger daily ranges and faster moves through price levels. The gamma flip level marks where this regime shift occurs.

Why does price tend to pin to high GEX strikes?

High OI strikes create hedging gravity. As price approaches, dealers holding short options at that strike must continuously adjust their delta hedge, buying when price drops below, selling when it rises above. This mechanical back-and-forth pulls price toward the strike and compresses volatility around it. Effect strengthens near expiration as gamma increases.

How is gamma exposure calculated from open interest?

GEX = Gamma × Open Interest × 100 × Spot². The formula weights each strike's open interest by its gamma value and the underlying's price squared. Aggregating across all strikes and expirations gives net dealer gamma. Positive values at calls, negative at puts, summed together. The spot-squared factor makes GEX scale with price level.

What's the difference between call-side and put-side GEX?

Dealers are typically short calls and short puts from customer flow. Short calls create positive gamma above spot (dealers buy dips). Short puts create positive gamma below spot but flip to negative when they go ITM (dealers then sell declines). The put wall (highest put-side GEX) is often monitored as potential support; the call wall is commonly interpreted as potential resistance.

Last updated: January 30, 2026