What Is Gamma Exposure?
Gamma exposure (GEX) is an estimate of how many shares market makers must buy or sell to stay delta neutral when price moves one point. It is not a prediction — it is a map of forced flow. Once you can read it, a lot of otherwise random intraday behaviour becomes mechanical.
Dealers are not taking a view
When you buy a call, someone sold it. That someone is usually a market maker who does not want directional risk, so they immediately hedge with shares. As price moves, the option's delta changes — that rate of change is gamma — and the hedge has to be adjusted continuously.
Long gamma dampens, short gamma amplifies
If dealers are net long gamma, their re-hedging sells rallies and buys dips: realized volatility compresses and price tends to range. If they are net short gamma, they must buy strength and sell weakness, which adds fuel to the move and expands volatility. Same market, opposite behaviour.
- Positive net GEX: mean reversion, tight ranges, fading extremes works.
- Negative net GEX: trend days, gaps that keep going, fading gets punished.
- The size of net GEX matters as much as the sign — small positive GEX is nearly neutral.
How the number is built
For each strike, GEX ≈ open interest x gamma x contract multiplier x spot, signed by an assumption about dealer positioning (dealers long calls sold to customers, short puts bought by customers). Summing across strikes gives net GEX; plotting it by strike gives the profile you see on the Gamma map.
What GEX is not
It is not a directional signal, it is not a guarantee of support, and it is stale the moment large new flow prints. Treat it as a conditional probability filter on top of your own thesis, refreshed intraday.
Interactive: move spot and watch GEX change
Positive gammaDealers sell rallies and buy dips to stay neutral.
Volatility compresses. Ranges hold, extremes get faded back toward the middle.
Illustrative model for teaching only — the live profile on the Gamma map is computed from the real chain.
Key takeaways
- GEX estimates forced dealer hedging flow, not opinion.
- Positive gamma compresses volatility; negative gamma amplifies it.
- Always check the sign and the magnitude before choosing a strategy.
Practice this in the terminal
FAQ
Do I need to compute GEX myself?
No. The Gamma map computes it live from the option chain; your job is interpretation and refresh discipline.
Which tickers give clean GEX?
Index products (SPY, QQQ) and mega-caps with deep chains. Thin chains produce noisy, unreliable profiles.
Test your knowledge
3 questions. Score 80% or higher to count this guide as mastered.
Keep going
Educational content only. Options involve substantial risk and are not suitable for every investor. Nothing here is financial advice.