Metric reference

Gamma Exposure (GEX) Explained — Dealers, Zero Gamma, Limits

Understand Bitcoin options gamma exposure, the dealer positioning it assumes, the zero gamma level, vanna and charm, and why GEX is a model of hedging rather than a measurement.

Read gamma exposure live on Bitcoin options, merged across Deribit, OKX, Bybit and Binance.

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What gamma exposure actually measures

Gamma is how fast an option’s delta changes as the underlying moves. Gamma exposure multiplies each contract’s gamma by its open interest and the square of the underlying price, giving the dollar value of delta a dealer would need to re-hedge for a one percent move.

The sign depends on who is long. No venue publishes positioning, so gamma exposure charts assume it: the common convention is that customers sell calls and buy puts, leaving dealers long calls, which dampen moves when hedged, and short puts, which amplify them.

Net positive gamma under that assumption means dealer hedging buys dips and sells rallies; net negative means it sells into declines and buys into rallies. The zero gamma level is the underlying price where the modelled total changes sign, and vanna and charm describe how the same hedges change with volatility and with time.

Core relationship

GEX per 1% ≈ Σ sign × Γ × OI × F² × 0.01, sign = +1 for calls and −1 for puts under the dealer assumption

The data contract

Before comparing two values, make sure they answer the same question.

The gamma must come from a model on each expiry’s forward and implied volatility; Basis uses undiscounted Black-76, the convention the venues price with.
Open interest must be converted to coins per venue before summing, because contract sizes and quoting units differ across exchanges.
The positioning assumption is part of the number. A chart that does not state it is presenting a model as a measurement.
The zero gamma level is found by moving every forward in proportion to a hypothetical index and recomputing gamma, so it is a reading for the current open interest and volatility, not a fixed line.

Read it in combinations

Observed together	Plausible interpretation	What would contradict it
Net GEX positive · index above zero gamma · realised volatility low	Modelled dealer hedging leans against moves, consistent with a compressed range.	A catalyst drives price below the zero gamma level and realised volatility expands.
Net GEX negative · price falling · put open interest dense below	Modelled hedging adds to the decline as price moves into short-gamma strikes.	Puts are closed or rolled lower, open interest thins and the move stalls without hedging pressure.
Large expiry near · charm exposure large	Dealer delta drifts quickly as time passes, so hedges change even with price flat.	Most of the open interest at the expiry is far from spot, where charm is small.
Implied volatility dropping · vanna exposure large and positive	Falling volatility reduces modelled dealer delta, which re-hedging turns into buying.	The actual holders are not the ones the convention assumes, as block trades or flow would reveal.

A reproducible workflow

01
State the assumption
Write down the positioning convention before reading the chart; every conclusion inherits it.
02
Locate the index against zero gamma
Note which modelled regime price is in and how far it is from the level where the sign changes.
03
Find the dominant strikes and dates
Use the by-strike chart and the expiry chips to see whether a few strikes on one date drive the total.
04
Check it against flow
Compare with the options flow: if customers are buying calls rather than selling them, the convention is wrong for that strike and the sign flips.

Common interpretation errors

Treating gamma exposure as measured dealer positioning.
Reading positive GEX as a guarantee that price cannot trend.
Ignoring that open interest near expiry disappears at settlement and changes the profile overnight.
Summing contracts across venues without converting to coins.

Questions

Why do dealers long calls and short puts in the model?+

Because the typical customer in crypto options sells calls against holdings and buys puts for protection, leaving market makers on the other side. It is a convention, and specific strikes can be the opposite; comparing with taker flow is how to catch that.

What is the zero gamma level?+

The underlying price at which modelled net dealer gamma changes from positive to negative. Above it, hedging is modelled to dampen moves; below it, to amplify them. It shifts as open interest and implied volatility change.

Are vanna and charm more useful than gamma?+

They answer different questions. Gamma is about price moving; vanna about implied volatility changing; charm about time passing. Near a large expiry, or after a sharp volatility move, the delta that vanna and charm describe can matter more than gamma.

All options analytics are freeOpen interest, implied volatility, dealer gamma, flow and the chain across four venues.See what is included Complete derivatives workflowApply the metrics in the terminal without double-counting evidence.Read the docs

Max painRead guide IV and skewRead guide Open interestRead guide