How to read a gamma exposure (GEX) chart

Every line on the terminal, and what it is actually claiming

A gamma exposure chart is not a price indicator. It is a picture of an obligation: how much index exposure dealers must buy or sell, mechanically, to stay hedged if the market moves from here. Read it as a map of where hedging flow concentrates — never as a forecast. If the term itself is new, start with what GEX is and come back.

The gamma ladder

The core of the chart is dealer gamma broken out by strike. Bars reach one way where dealers are net long gamma and the other way where they are net short. The shape carries more information than any single bar: a ladder piled up on one side of spot says hedging pressure is one-sided and directional moves will meet resistance or fuel depending on which side; a ladder balanced around spot says the board is crowded both ways and price has every reason to sit still.

FLIP — the line that splits the regime

The FLIP line marks the index level where aggregate dealer gamma crosses zero. Above it, hedging leans against the tape and dampens moves; below it, hedging leans with the tape and amplifies them. It is the single most useful line on the chart, and the most often misread: it is not support, not resistance, and not a signal to do anything. It tells you which of two markets you are trading in. Full explanation on the zero-gamma flip line.

CR and PS — the walls

CR (call resistance) marks the strike carrying the heaviest dealer gamma above spot, PS (put support) the heaviest below. Approaching either one, hedging intensifies against the move, which is why price so often stalls or pins there. They are concentrations, not barriers — and in the 0DTE era they migrate through the session as flow arrives. See call resistance and put support.

The expected-hold band

The band is the range those gamma concentrations implied for the session. Its value is in the record: every archived session states whether the day stayed inside it or traded out, so the band's hit rate is something you can check yourself rather than take on faith.

Net-gamma percentile — is today actually unusual?

A raw GEX number answers nothing on its own; nobody has an intuition for whether a given net gamma is large. The percentile fixes that by ranking measured dealer gamma at spot against every minute of the trailing twenty sessions. Near 100 the book is more loaded than it has been all month — a genuinely pinned tape. Near 0 it is thin, with little to absorb a move. The middle is most days, and most days the chart is not telling you anything worth acting on.

What a GEX indicator cannot tell you

Direction. Open interest is not observable intraday, initiator classification is probabilistic, and the dealer-book reconstruction carries real error bars. This site tested directional rules on years of its own data and found nothing worth an arrow — which is why the terminal draws none. A gamma exposure chart describes the mechanics around a move; it does not predict the move.

Read one on a real session

The fastest way to learn the chart is to run it against days you remember. Every archived session is free to replay minute by minute — the ladder, the flip, the walls and the band as they actually moved. Nothing here is investment advice; see the Terms.