Reading the market regime before prices move
Reading the market regime before prices move
One page with what you need to know about dealer positioning: from the definition of the indicator to reading the Gamma Flip and the walls on a real symbol.
Gamma Exposure (Gamma Exposure · GEX) One number that sums up how many shares dealers would have to buy or sell if price moved 1%. It is based on Gamma · Γ, how fast delta changes (Gamma · Γ) : each open contract's gamma is multiplied by Open Interest (Open Interest) and in the price square, then the signals are summed across all strikes and expirations. The result does not say where price will go. It says how those hedging against it will act when it moves.
Because a market maker is direction-neutral by the nature of the job: they sell the contracts the public asks for and hedge the risk with the shares themselves. When their gamma position is positive, they sell into rises and buy into falls, which absorbs the move. When it is negative, they do the opposite and amplify it. Gamma exposure measures this effect before it happens, and that is all it promises.
Gamma Flip (Gamma Flip) It is the price level where net gamma turns from positive to negative. It is found by repricing the gamma of all open contracts on a grid of assumed prices around the current price, then looking for the nearest crossing of zero. Above it damping dominates, below it acceleration dominates, and the distance to it in percent is the first number to read on the page.
A price less than 0.5% from the Flip means the regime is fragile and can flip within the same session. A price more than 1.5% away means a regime that is stable for a while. The value changes with every open interest update, so the calculation date is part of the number, not a footnote.
Call Wall (Call Wall) It is the strike where the largest call gamma is concentrated, and the Put Wall (Put Wall) Its counterpart for puts. At the first, dealers tend to sell into rises, so price slows near it. At the second, they tend to buy into falls, so price finds support. The two walls are likely slowing levels, not a guaranteed ceiling or floor.
A wall loses its effect when open interest migrates from it to another price, when its expiration nears and its gamma evaporates, or when price crosses it on heavy volume and hedgers are forced to reverse their positions. So next to each wall the platform shows today's volume against yesterday's contracts, because a ratio above 1 means the wall is being rebuilt or taken apart right now.
The classic calculation assumes the public buys puts for protection and sells calls for income, which leaves the market maker long call gamma and short put gamma. That is an assumption, not a measurement. So the gamma pages show a second reading beside it, taken from trade execution on the most active contracts. If it agrees with the assumption, confidence in it rises. If it disagrees, read the signal with caution.
Multi-leg trades print leg by leg, so they look aggressive when they are neutral. Hedging outside the options market does not show up at all. Contracts expiring today carry huge gamma that hides the structure further out. So the platform separates today's expiration from the week and from the longer term, and never merges them into one number.
The reading order is fixed: the signal first, then the distance to the Gamma Flip, then the two walls, then what is happening at them today.
| Step | What to look at | What it means |
|---|---|---|
| 1 | Net gamma signal | Positive dampens the move, negative amplifies it |
| 2 | Distance to the Gamma Flip | Close means a fragile regime, far means a stable one |
| 3 | Where price sits between the two walls | Approaching a wall suggests possible slowing, not a guaranteed bounce |
| 4 | Today's volume against yesterday's contracts at the wall | A ratio above 1 means the wall is changing now |
| 5 | Order flow at the wall | A majority of volume classed as selling or buying describes pressure and does not give a verdict |
On SPY at a price of $778.01 net gamma is positive, so the regime is damping. The Gamma Flip is at $777.07 and price is above it by 0.12%. The Call Wall is at $785.00 and the Put Wall at $778.00. The numbers come from the latest published calculation , with full detail on the SPY gamma page.
Gamma exposure is built on open interest as of its last update, so it is a picture of yesterday read today. It assumes a direction of positioning that is not measured directly. It misleads when today's expiration is mixed with later ones, when a wall is read as a ceiling instead of a slowing level, and when you forget that one headline can push through any wall. It misleads most when read alone, without volume, flow or context.
It shows each number's source and date, separates the three horizons, puts a flow reading and the execution side next to the structure, and states a gap in words, not as a zero. Everything on this page describes how the market works. It explains and simplifies, and it is not a call to enter or exit.
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