What is GEX (Gamma Exposure)?
GEX (Gamma Exposure) is a measure that helps you understand how market makers’ hedging behaviour can influence price moves. It is one of the most useful concepts for reading the intraday session, especially on short expirations such as 0DTE.
Gamma and GEX in short
Section titled “Gamma and GEX in short”Two option concepts lead to GEX:
- Delta — how much the option price moves when the underlying moves.
- Gamma — how quickly delta changes as the underlying moves; in practice, the “acceleration” of delta.
GEX is the aggregate gamma of all the options open on an instrument: it measures how much hedging market makers have to do to stay neutral as price changes.
Why it matters, especially on 0DTE
Section titled “Why it matters, especially on 0DTE”Close to expiration gamma grows a great deal: market makers have to hedge more intensely, and that mechanical activity becomes a concrete force in the market. This is why GEX is particularly significant on very liquid instruments and on daily expirations.
The effect on price
Section titled “The effect on price”| Regime | Market maker behaviour | Typical effect on price |
|---|---|---|
| Positive GEX (Long Gamma) | Buy on dips, sell on rallies | Lower volatility, market tending to revert to the mean (range) |
| Negative GEX (Short Gamma) | Sell on dips, buy on rallies | Higher volatility, amplified moves (breakout) |
The level where exposure changes sign is the key reference: see Gamma Flip (Gamma 0).
Where to see it in the app
Section titled “Where to see it in the app”GEX is available in three places, and they answer different questions:
- GEX Gaudio — the live SPX gamma profile by price level, with market maker levels and the SPX-to-ES conversion.
- GEX Open Interest — gamma exposure per strike computed on the open contracts of the active symbol: the accumulated state.
- GEX Volumes — gamma exposure per strike computed on today’s traded volume: what is being created now.
All three belong to the Premium and Ultra plans.
Common mistakes
Section titled “Common mistakes”- Reading GEX as a direction forecast. It describes a hedging regime, which conditions how price moves, not where it goes.
- Applying it to illiquid instruments. With little option volume there is no meaningful aggregate gamma to speak of.
- Ignoring the expiration. GEX computed on a far expiration says little about the next hour; the short expirations dominate intraday.
- Treating the flip level as fixed. It moves with positioning through the session.
Frequently asked questions
What is GEX in options trading?
GEX, short for Gamma Exposure, is the aggregate gamma of all options open on an instrument. It measures how much hedging market makers must do to stay neutral as the underlying price moves, and therefore how their mechanical activity can influence price behaviour.
What is the difference between delta and gamma?
Delta is how much an option price moves when the underlying moves. Gamma is how quickly delta itself changes as the underlying moves, in practice the acceleration of delta.
What does positive GEX mean?
Positive GEX, also called long gamma, means market makers buy on dips and sell on rallies. The typical effect is lower volatility and a market that tends to revert to the mean, producing ranges rather than trends.
What does negative GEX mean?
Negative GEX, also called short gamma, means market makers sell on dips and buy on rallies. The typical effect is higher volatility and amplified moves, favouring breakouts over ranges.
Why does GEX matter most on 0DTE options?
Because gamma grows sharply as expiration approaches. Market makers then have to hedge much more intensely, so their activity becomes a concrete force in the market. That is why GEX is most significant on very liquid instruments with daily expirations.
Where can I see GEX in Gaudio OTT?
On the GEX Gaudio page, which shows the live SPX gamma profile by price level, and on the intraday GEX Open Interest and GEX Volumes charts for the active symbol. All three are available on the Premium and Ultra plans.
Related pages
Section titled “Related pages”Ready to use Gaudio OTT?
Section titled “Ready to use Gaudio OTT?”Open your free account and put what you just read into practice.