Gamma Exposure (GEX)
Gamma exposure (GEX) is an estimate of how much option market-makers must buy or sell the underlying to stay hedged as its price moves, aggregated across strikes. When dealer GEX is net positive, hedging tends to dampen price moves; when it is net negative, hedging tends to amplify them.
Every option a dealer holds has a gamma - the rate at which its delta (directional exposure) changes as the underlying moves. To stay delta-neutral, dealers re-hedge as price moves, and the size and direction of that hedging flow depends on their aggregate gamma position. GEX sums that effect across all listed strikes to estimate the net hedging pressure the dealer complex exerts on the market.
The sign matters more than the exact dollar figure. In a positive-gamma regime, dealers sell into rallies and buy into dips, which compresses the trading range and absorbs shocks. In a negative-gamma regime, they buy into rallies and sell into dips, which mechanically amplifies moves - the same dynamic that turns an ordinary catalyst into an outsized session.
GEX is an estimate, not a measured fact: it depends on assumptions about which side of each contract dealers hold. It is most useful read directionally (positive vs. negative, and where the flip sits) rather than as a precise number.
Frequently asked
Does positive GEX mean the market will go up?
No. GEX describes volatility, not direction. Positive dealer gamma tends to dampen the size of moves in either direction; it says nothing about whether price rises or falls.
Is GEX a precise measurement?
No. GEX is an estimate that depends on assumptions about dealer positioning. It is best read as a sign (positive/negative) and a structure (where the walls and flip are), not an exact dollar value.
Related terms
This term is part of a bigger picture: Gamma Exposure, Explained — the complete guide →