GEX & Dealer-Flow Glossary

Gamma Exposure (GEX) measures how much options dealers must buy or sell to stay delta-hedged as the underlying price moves.

Gamma Exposure aggregates the gamma of every option on a chain into a single curve that shows where dealer hedging will absorb or amplify price moves. Positive total GEX implies dealers buy dips and sell rips (volatility dampened); negative total GEX implies they sell weakness and chase strength (volatility amplified).

Also known as: GEX · gamma exposure · options gamma

Net GEX is the sum of call gamma minus put gamma across all strikes, summarizing the market-wide dealer gamma sign.

Net GEX collapses the whole profile into one number: a large positive value points to a pinning, mean-reverting tape, while a negative value warns of trend-prone, high-volatility conditions. Traders watch when Net GEX crosses zero as a regime change signal.

Also known as: net gamma exposure · total gex

Zero Gamma is the price level where net dealer gamma flips from positive to negative, marking the boundary between volatility suppression and amplification.

Above the zero-gamma (flip) level dealers are typically long gamma and dampen moves; below it they are short gamma and accelerate them. Because behavior changes sign there, the flip level often acts as a pivotal intraday support/resistance.

Also known as: gamma flip · flip level · zero gamma level · gamma flip point

The Call Wall is the strike with the largest call gamma, which tends to act as resistance / a price magnet.

Heavy dealer call gamma concentrated at one strike forces sustained selling as price approaches, which frequently caps rallies into expiration. A break above the call wall can flip prior resistance into a fast-move zone.

Also known as: call resistance · gamma resistance

The Put Wall is the strike with the largest put gamma, which tends to act as support / a downside floor.

Concentrated dealer put gamma drives buying as price falls toward the strike, which often cushions sell-offs. Losing the put wall removes that support and can open the door to accelerated downside.

Also known as: put support · gamma support

In a long-gamma regime dealers hedge against the move (buy dips, sell rips), which suppresses realized volatility.

Long-gamma conditions usually produce range-bound, mean-reverting price action with shallow pullbacks. They typically occur when the underlying trades above the zero-gamma level.

Also known as: positive gamma · long gamma

In a short-gamma regime dealers hedge with the move (sell weakness, buy strength), which amplifies realized volatility.

Short-gamma conditions favor trends, gaps, and momentum cascades because hedging adds fuel to the prevailing direction. They typically occur when the underlying trades below the zero-gamma level.

Also known as: negative gamma · short gamma

Dealer positioning describes the net options inventory market makers hold and the hedging flows it forces them to execute.

Because dealers must hedge their books, their aggregate gamma, vanna, and charm exposure becomes a predictable, mechanical source of buying and selling. Reading that positioning lets traders anticipate where flows will support or pressure price.

Also known as: market maker positioning · dealer hedging

Charm is the rate at which an option’s delta changes as time passes, driving predictable dealer hedging into the close and expiration.

As expiration nears, charm pulls option deltas toward 0 or 1, forcing dealers to mechanically adjust hedges — often producing the late-day drift and end-of-week flows traders track. Charm effects are strongest around large open-interest strikes.

Also known as: charm · delta decay · DdeltaDtime

Vanna measures how an option’s delta shifts when implied volatility changes, linking volatility moves to dealer hedging flows.

When implied volatility falls (e.g. a “vol crush”), vanna forces dealers to buy the underlying, fueling the classic rallies seen after fear subsides. Rising volatility works in reverse, adding selling pressure.

Also known as: vanna · DdeltaDvol

HVL marks the price area where dealer gamma turns most negative, flagging the zone where volatility is likely to expand fastest.

Trading into the HVL warns that hedging flows will accelerate rather than absorb moves, so breaks through it often coincide with the day’s sharpest swings. It complements the zero-gamma level as a volatility road map.

Also known as: high volatility level · hvl

0DTE options expire the same trading day, so their gamma is extreme and dealer hedging can dominate intraday price action.

Because 0DTE gamma spikes near the money, even small spot moves trigger large hedging flows that create pinning into key strikes or violent breakouts when those strikes fail. This makes intraday GEX especially important for 0DTE-heavy markets.

Also known as: zero days to expiration · 0 DTE · same-day options