Gamma Exposure (GEX)
Gamma Exposure (GEX) describes how option gamma is distributed across strikes for a given expiry, weighted by open interest. It provides a structured view of where convexity is concentrated in the listed options market and how sensitivity to price movement varies across the strike space.
The Reflex Research GEX dataset is constructed entirely from observable, mechanically defined quantities derived from listed options. Call and put gamma are treated symmetrically and aggregated by strike, without assumptions about who holds the positions or how they are hedged.
At its core, GEX answers a focused structural question: where in price space is option convexity concentrated, and how sensitive is the market to small underlying price movements at those levels?
Gamma governs how rapidly option delta changes as price moves. When gamma is concentrated around certain strikes, small changes in the underlying can coincide with non-linear changes in market dynamics. Mapping this convexity structure provides context for volatility regimes, price stability, and transitions between mean-reverting and trending behaviour.
This framework is now widely studied in quantitative finance and market-structure research. The references below reflect academic and practitioner work that examines the relationship between option gamma, volatility, and price dynamics, and align with the structural quantities captured by the Reflex Research GEX dataset.
-
Gustav Jonsson and Theo Nyberg —
Convexity in Motion - Leveraging Gamma Exposure to Predict Equity Market Returns and Improve Predictive Modeling
-
SqueezeMetrics —
The Implied Orderbook
-
Amar Soebhag —
Option Gamma and Stock Returns
In practice, GEX is best understood as a market structure indicator rather than a directional signal. It is commonly used to identify regions of high convexity, compare convexity profiles across expiries, and monitor how the distribution of gamma evolves through time.
As with other options-implied measures, the value of GEX lies in understanding how the market is structurally arranged at a given moment. It does not attempt to infer positioning or predict future prices, but instead provides context for price behaviour, volatility regimes, and options strategy construction.