What is Gamma Exposure (GEX)?
Gamma Exposure (GEX) measures the total gamma risk that options market makers and dealers hold at each strike price. When traders buy options, dealers take the opposite side of the trade and must hedge their positions by trading the underlying stock. The amount they need to hedge changes based on gamma—the rate at which delta changes as the stock price moves.
Understanding aggregate GEX helps traders predict how dealer hedging flows will impact stock prices. High positive GEX at a strike creates a "gamma wall" that acts as a price magnet, while negative GEX environments can lead to explosive moves known as gamma squeezes.
How is Gamma Exposure Calculated?
GEX is calculated by multiplying open interest, gamma, stock price, and contract size for each option. The key insight is that calls and puts have opposite effects on dealer hedging:
Call GEX = Open Interest × Gamma × Stock Price × 100
Put GEX = -Open Interest × Gamma × Stock Price × 100
Net GEX = Call GEX + Put GEX
The negative sign for puts reflects that dealers are typically short puts. When the stock rises, dealers must sell shares to hedge (opposite of calls where they must buy). This creates the push-pull dynamic that drives price behavior around high-GEX strikes.
Key GEX Levels to Watch
Gamma Wall
The strike with the highest positive GEX concentration. Acts as a strong price magnet where the stock tends to gravitate toward and consolidate. Dealers buy dips and sell rallies around this level, suppressing volatility.
Zero Gamma Level
The price where net GEX flips from positive to negative. Below this level, dealer hedging amplifies moves. Above it, hedging dampens moves. Critical for understanding volatility regimes.
Max GEX Strike
The strike with the largest absolute GEX value. Often coincides with round numbers or significant technical levels. Price tends to pin near this level during options expiration.
GEX Flip Level
Similar to zero gamma, this is where the market transitions between stable (positive GEX) and volatile (negative GEX) regimes. Breaking through this level can trigger accelerated moves.
Positive vs Negative Gamma Environments
Positive Gamma (Dealers Long Gamma)
- Volatility Suppression: Dealers buy when price falls and sell when price rises, creating mean-reversion pressure.
- Price Magnetism: Stock tends to gravitate toward high-GEX strikes, especially near expiration.
- Range-Bound Trading: Expect tighter ranges and smaller daily moves.
- Strategy Implication: Favor selling premium, iron condors, and mean-reversion strategies.
Negative Gamma (Dealers Short Gamma)
- Volatility Amplification: Dealers sell into weakness and buy into strength, accelerating moves in both directions.
- Gamma Squeeze Risk: Sharp moves can trigger cascading hedging flows, creating explosive price action.
- Trending Markets: Expect larger daily ranges and directional momentum.
- Strategy Implication: Favor buying options, momentum strategies, and breakout plays.
How to Use This GEX Calculator
- 1
Enter Stock Price
Input the current stock price as a reference point for identifying ATM strikes and calculating relative GEX levels.
- 2
Add Option Chain Data
Enter strike prices, option type (call/put), open interest, and gamma for each contract. Include strikes above and below the current price for complete analysis.
- 3
Analyze the GEX Profile
Review the chart to identify gamma walls, zero gamma levels, and the overall GEX environment (positive or negative).
- 4
Apply to Trading Decisions
Use GEX levels as support/resistance zones, adjust position sizing based on gamma environment, and anticipate volatility changes.
Trading Strategies Using GEX
Gamma Wall Trading
When price approaches a gamma wall from below, expect resistance as dealers sell into the rally. When approaching from above, expect support as dealers buy the dip. Trade mean-reversion setups toward the gamma wall, especially during positive gamma environments.
Zero Gamma Breakout
When price breaks through the zero gamma level, volatility often increases as the market transitions to a negative gamma regime. This can be a signal to buy options or position for larger moves. Conversely, crossing back above zero gamma suggests volatility compression.
Expiration Week Pinning
During options expiration week, GEX effects are strongest. Price tends to "pin" near high-GEX strikes as dealers' hedging flows dominate. Identify the max GEX strike early in the week and position for convergence toward that level.