Definition · updated 2026-10-21
GEX (gamma exposure)
GEX, or gamma exposure, is the number of shares options dealers must buy or sell to stay hedged for a 1% move in the underlying, summed across every strike. Positive GEX means dealer hedging dampens moves; negative GEX means it amplifies them.
See it live: today's GEX levels by ticker.
How GEX is computed
For every open contract: open interest × gamma × 100 × spot² × 1%. Calls count positive and puts negative, because dealers are short the options the public owns and hedge in the opposite direction. Sum by strike for the profile; sum everything for net GEX.
The strike with the most call gamma is the call wall, the strike with the most put gamma is the put wall, and the price where cumulative GEX crosses zero is the gamma flip.
Why traders watch it
In positive gamma, dealers sell rallies and buy dips, so the tape pins and ranges hold. In negative gamma they do the opposite, so moves extend. Knowing which regime you are in tells you whether to fade or follow, and the walls give you levels with a mechanical reason behind them.
GEX is not a forecast. It describes hedging pressure that exists today and moves as open interest changes.
Example
SPY trades at 770 with the call wall at 775 and the put wall at 760. A rally into 775 meets dealers selling to hedge; a dip to 760 meets dealers buying. A day trader uses the walls as targets and the flip as the line where the regime, and the plan, changes.
Frequently asked questions
- What does GEX stand for?
- Gamma exposure: the aggregate share-hedging obligation of options dealers for a 1% move in the underlying.
- Is high GEX bullish or bearish?
- Neither on its own. High positive GEX means moves are dampened and ranges tend to hold; negative GEX means moves are amplified in both directions. Direction comes from elsewhere.
- How do I get GEX levels for free?
- OptionScout publishes daily GEX levels for the tickers it captures on its gamma exposure pages, and the app shows levels on every US ticker on the free plan.