What the zero gamma level is
Zero gamma (also called the gamma flip level) is the spot price at which aggregate dealer gamma exposure, as modeled across the options chain, crosses from positive to negative. Above it, the hedging implied by the model dampens moves. Below it, the same hedging amplifies them. It is the single level in gamma analysis that describes a change in market behavior rather than a change in price.
The important word in that paragraph is modeled. Everything below explains why.
The sign convention most explainers get backwards
Gamma is a property of optionality, not of direction. Long options are positive gamma, whether they are calls or puts. Short options are negative gamma, whether they are calls or puts. Buying a put does not give you negative gamma because puts are bearish. It gives you positive gamma because you are long an option.
Work the hedging through, because this is where the sign actually bites. A dealer short a put holds a position with positive delta, say +0.5 at the money. As spot falls, that short put's delta becomes more positive, moving toward +1. The dealer hedged this by shorting 0.5 units of the underlying. Now spot drops, position delta rises to +0.8, and against a -0.5 hedge the dealer is left +0.3 long. To return to neutral they must sell more underlying, into a market that is already falling.
That is negative gamma in one sentence: the hedge sells declines and buys rallies, so it feeds the move. The dealer is not choosing to press the market; the arithmetic of staying delta-neutral requires it.
A dealer who is long options faces the mirror. Their hedge requires buying as spot falls and selling as it rises, which absorbs order flow and compresses realized volatility. That is the positive gamma regime.
Above and below the flip
Above the zero gamma level, the modeled book is net long gamma. Expect mean reversion, contained ranges, and dips that get bought by hedging flow rather than conviction. Realized volatility tends to run below what implied volatility priced.
Below it, the modeled book is net short gamma. Hedging turns procyclical, ranges widen, and moves that would otherwise fade instead extend. This regime is covered in more depth in negative gamma explained.
The level itself is not fixed. It is recomputed from the current chain, so it drifts as open interest builds and shifts, and it can relocate sharply after OPEX retires a large block of contracts.
The assumption underneath it
Here is what most zero gamma content will not tell you: dealer positioning is an assumption, not an observable. Open interest tells you that a contract exists at a strike. It never tells you which side of it a dealer is on.
Every published gamma flip level therefore rests on a sign convention imposed by the model, conventionally, that dealers are long calls and short puts, on the reasoning that customers buy downside protection and sell upside. Sometimes that convention is right. At any particular strike it may be entirely wrong, and where it is wrong, the gamma attributed to that strike does not exist and the flip level computed from it is off. Our dealer positioning guide covers how these inferences are built and where they fail.
This does not make the level useless. It makes it a hypothesis with a measurable track record, which is a different and more honest thing than a line on a chart presented as fact.
Whether the level actually holds
The question worth asking about any gamma level is not whether a provider can draw it, but how often it has held when price genuinely reached it. Almost no one in this category publishes that number, and as of August 2026 we no longer do either. We showed one and withdrew it: it was measured against a third-party definition of a wall, and it counted every quiet day the level was never approached as a hold, which is how a distant level scores near ninety percent while the near-money tests come in close to a coin flip. Our free SPX gamma exposure page now publishes the flip with the time the snapshot was captured and a timestamped log of what the structure did through the session, and the Start Here path walks through counting the touch-conditioned version yourself.
For the calculation mechanics, see what is gamma exposure and the GEX flip price breakdown.
Educational content, not financial advice. See our risk disclosure.