Gamma Exposure (GEX)

TL;DR: Gamma exposure (GEX) is computed from options open interest and marks strikes where a stock's price has tended to pin in place or accelerate.

Gamma exposure, or GEX, aggregates option gamma across all strikes and expirations for a given stock or index, computed from published open interest. Gamma itself is the rate of change of delta — it tells you how quickly an option's directional sensitivity changes as the stock moves. GEX takes this to the market level. Note what it is: an inference from open interest under a sign convention, not an observation of anyone's actual book. Dealer and market-maker inventory is not publicly reported.

The standard interpretation runs like this. Where GEX is high and positive, hedging a short-gamma-free book means selling as the stock rises and buying as it falls — a stabilizing force that tends to "pin" price near that strike, especially approaching expiration. Where aggregate GEX is negative, the same hedging logic runs the other way and amplifies moves, creating a feedback loop that increases volatility. Empirically, price has behaved this way around these strikes often enough to be measurable; the mechanism is the conventional explanation for it, not something we verify directly.

Understanding GEX helps explain seemingly irrational price behavior. Stocks that appear "stuck" at a price near expiration are often being pinned by high positive gamma at that strike. Stocks that seem to accelerate in one direction may be experiencing negative gamma dynamics. Options Pilot tracks open interest walls and gamma risk within the Timing pillar, identifying where significant OI concentrations exist, what the max pain level is, and whether pin probability is high — giving you awareness of the mechanical forces that can override fundamental analysis near expiration. TradeSignals shows put walls and call walls computed from open interest.