What is Gamma Exposure (GEX)?

What GEX actually measures

Every option has gamma — the rate at which its delta changes as the underlying moves. Dealers who are short options must trade the underlying to stay delta-neutral, and gamma tells you how aggressively. GEX aggregates that hedging pressure across the whole options chain so you can see where dealers are forced to act.

The practical payoff: GEX turns a raw options chain into a map of dealer positioning — where volatility gets suppressed, where it accelerates, and which strikes behave like magnets, walls and flip points during the session.

How GEX is calculated

For each strike, gamma exposure is approximately:

• GEX ≈ Gamma × Open Interest × Contract Multiplier × Spot² — computed per strike, then summed across the chain.
• Call gamma counts as positive dealer exposure and put gamma as negative (the standard dealer-sign convention).
• Near-term options dominate the profile naturally, because gamma rises sharply into expiration (gamma ∝ 1/√T) — no artificial time-decay weighting is needed.
• Summing signed GEX across every strike gives net GEX for the underlying, and the strike-by-strike profile reveals the structural levels below.

Long gamma vs short gamma: the two regimes

The single most useful thing GEX tells you is which volatility regime the market is in — set by whether spot is above or below the zero-gamma flip.

• Positive (long) gamma — spot above zero gamma: dealers buy dips and sell rips to stay hedged. This dampens volatility and pulls price back toward equilibrium (mean-reversion, tight ranges).
• Negative (short) gamma — spot below zero gamma: dealers sell dips and buy rips. This amplifies moves, so trends accelerate and volatility expands (breakouts, air pockets).

Key GEX levels every trader watches

A GEX profile is read through a handful of structural levels:

• Zero Gamma (0Γ) — the price where net dealer GEX flips sign; the bull/bear decision line between the two regimes above.
• HVL (Highest Volatility Level) — the strike at the peak of the net-GEX curve; the formal volatility-regime divide.
• Call Wall — the strongest call-side gamma concentration; powerful overhead resistance price struggles to break.
• Put Wall — the strongest put-side gamma concentration; downside support where falling price is often pulled back.
• Absolute-gamma peak — the single largest total-gamma strike; the market’s strongest “magnet”, where price tends to pin.

How to read and trade GEX

A repeatable framework is Regime → Structure → Confirmation:

• Regime: is spot above or below zero gamma? Above = fade extremes; below = respect trend and cut size.
• Structure: use the call wall / put wall as intraday targets and defense levels; expect reactions there.
• Confirmation: pair the map with real-time hedging flow and price action before acting — GEX tells you where, flow tells you when.

GEX and 0DTE options

0DTE (zero-days-to-expiry) options carry enormous gamma right around spot, so their hedging flow can pin price to a strike or trigger sharp intraday moves once a wall breaks. Because that gamma decays and re-concentrates within the day, 0DTE GEX shifts fast — which is why an intraday, second-by-second GEX view matters far more than a static end-of-day chart for short-term traders.