Gamma Exposure
Gamma exposure (GEX) is an estimate of how strongly options market makers' hedges will change as the price moves. When dealers are long gamma, their hedging tends to dampen price swings; when they are short gamma, it can amplify them.
From delta and gamma to hedging
Delta measures how much an option's value changes when the underlying price moves by one unit. Gamma measures how fast delta itself changes. Market makers who sell options to traders usually hedge their delta in the spot or futures market so they are not betting on direction. Because gamma keeps changing their delta, they have to keep adjusting that hedge.
Gamma exposure adds this up across all open options. It takes the gamma of every strike and expiry, multiplies by open interest and contract size, and estimates how much the underlying asset dealers would need to buy or sell for a given move, often expressed per 1% change in price.
Positive vs. negative gamma
If dealers are net long gamma, a rising price increases their delta, so they sell to stay neutral; a falling price makes them buy. They trade against the move, which tends to keep the price in a range. If dealers are net short gamma, the logic flips: they must buy into rallies and sell into drops, adding fuel to whichever way the market is going.
Say dealers hold options positions whose combined delta grows by 10 BTC for every 1,000 rise in bitcoin. If the price climbs 1,000, they sell 10 BTC to hedge; if it falls 1,000, they buy 10 BTC. Scale that across a large options market and the flows can matter, especially near strikes with heavy open interest and close to expiry, when gamma is highest.
The limits of GEX
Nobody sees dealers' real positions. Public GEX figures rely on assumptions, typically that customers buy options and dealers sell them. If that assumption is wrong for a large trade, the sign of the estimate can be wrong too. Crypto options trading is concentrated on a few venues, and spot and perpetual futures activity often dwarfs hedging flows.
GEX also changes quickly: a big expiry can remove much of the gamma overnight. People lose money when they treat a positive GEX reading as a guarantee that the price will stay pinned, or a negative one as a signal of direction. It describes how hedging may react, not where the price will go.
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Frequently asked questions
What does positive gamma exposure mean?
It suggests dealers are net long gamma, so their hedging trades against price moves. That can make the market calmer and more range-bound, though other flows can easily overwhelm it.
What does negative gamma exposure mean?
It suggests dealers are net short gamma and must hedge in the direction of the move. That can make rallies and sell-offs faster and larger.
Is gamma exposure a buy or sell signal?
No. It is an estimate of hedging pressure based on assumptions about who holds which options. It says nothing reliable about direction on its own.
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