Summary. GEX dashboards report a short list of named levels: the gamma flip, call wall, put wall, vol trigger, max pain and sometimes a major wall. This reference explains what each level measures, how it forms, how traders read it and where it can mislead.
1. Gamma flip (zero gamma)
The gamma flip is the spot level at which net dealer gamma exposure changes sign. Above it, estimated dealer hedging leans against moves; below it, hedging adds to them. If is net dealer gamma exposure recalculated at a hypothetical spot , with positions, implied volatility and time held fixed, the flip is the level that solves
Because it solves an equation over a continuous range of prices, the flip is a price level, not necessarily a strike. It is also not the point where the bars on a GEX-by-strike chart change sign, nor where a running total of per-strike GEX crosses zero. Both shortcuts use gamma at today's spot only.
How traders read it. The flip is the main regime line for most GEX users. Sessions on one side of it tend to share a character, compression above and expansion below, and a cross often comes with a change in realized volatility because hedging flow reverses there. Research by Barbon and Buraschi links negative dealer gamma to intraday momentum.
2. Call wall
The call wall is the strike with the largest positive net GEX. Under the usual convention, which treats dealers as long the calls customers sell, it concentrates dealer long-gamma hedging on the upside: as price rises toward it, dealers sell, and the selling grows near the strike and as expiry approaches.
How traders read it. The call wall is treated as soft resistance. A sustained break usually needs demand from outside the hedging flow, after which the next large positive strike becomes the reference. Walls migrate as open interest rolls, tending to move up the chain in a rising market. If customer call buying built the strike, dealers are short gamma there and the level can extend a rally instead.
3. Put wall
The put wall is the strike with the largest negative net GEX. Under the convention, dealers are short the puts customers bought for protection, so they are short gamma at that strike: as price falls toward it, their hedge sells the underlying.
Hedging alone would make it a weak floor, yet it often acts as support. Put holders tend to take profits as price reaches their strike, and when dealers buy those puts back they also buy back the attached short hedges. In a market that is long gamma overall, aggregate hedging still leans against the decline. When the level gives way, the short gamma there adds to the selling, so breaks often coincide with a shift to higher volatility.
How traders read it. Many traders watch implied volatility during a test: rising demand for protection suggests the level is under pressure, while implied volatility that stops rising suggests the test is being absorbed. Repeated tests in a negative-gamma regime are treated as weaker support than a first test in a positive one.
4. Vol trigger
The vol trigger marks where dealer hedging becomes large enough to change the character of the market. The flip answers a sign question (where net gamma crosses zero); the trigger answers a magnitude question (where short-gamma hedging becomes large relative to available liquidity).
The term is practitioner vocabulary, and definitions differ. SpotGamma, which popularized it, describes its trigger as the last major level of positive gamma support, which can sit above zero gamma. Other implementations place it below the flip, where modeled dealer selling starts to accelerate, leaving a band where dealers are short gamma but amplification is still mild. Levels from different methods should not be compared directly.
How traders read it. A move down through the trigger is often read as the clearest sign in the GEX framework that the session's character has changed, and traders who use it allow for wider ranges below it. A reclaim from below is often the first sign of stabilization, ahead of a reclaim of the flip.
5. Major wall
Some dashboards also show a major wall: the strike with the largest net GEX in absolute terms, regardless of sign. In a positive-gamma market it often coincides with the call wall; in a negative-gamma market it can be the put wall. It is a quick read on which strike dominates the chain, but adds nothing beyond the two walls.
6. Max pain
Max pain is the settlement price at which the total intrinsic value paid to option holders would be smallest. For a settlement price , the payout across the expiring chain is
and max pain is the that minimizes . Because the payout is piecewise linear in , the minimum falls on a listed strike. It is not the same as the strike at which the most contracts expire worthless: max pain weights each contract by how far in the money it would finish, and a count of worthless contracts does not.
Max pain is an accounting quantity, not a hedging signal. It ignores gamma, the dealer's side of each position and how positions are hedged. The idea that dealers push price toward it assumes they are short every open option, and hedged dealers are largely indifferent to where settlement lands.
How traders read it. Pinning is documented: Ni, Pearson and Poteshman find that optionable stocks close near strikes more often on expiration dates, and attribute it partly to market makers' hedging. That evidence concerns heavily traded strikes, not the max-pain strike as such, so max pain is best treated as a low-confidence reference. Gamma at strikes near spot is a more direct read.
7. Secondary walls
After the primary walls, the next-largest positive and negative strikes are often labeled secondary walls. They matter most when the primary wall is far from spot, since price must pass the secondary level first, and they become primary when open interest migrates, for example after an expiration.
8. Putting the levels together
A complete read uses the levels together:
- The gamma flip sets the regime: stabilizing above, amplifying below.
- The call wall and put wall frame the range in which hedging flow is concentrated.
- The vol trigger shows where amplification becomes strong.
- Secondary walls show what sits beyond the primaries if they break.
- Max pain is a low-weight reference on expiration days.
All of these are estimates built on a sign convention and on open interest published once per day, so they shift with expirations, new positioning, implied volatility and time. The DataFirst terminal draws these levels; see options flow. For the underlying concept, start with what is gamma exposure.
For educational and informational purposes only. Not financial advice. Options trading involves substantial risk of loss.