THE LEXICON · GAMMA WALLS
Gamma walls
Gamma walls are the strikes carrying the heaviest concentrations of dealer gamma — usually large open-interest calls above spot and puts below. They mark where hedging flow is thickest, not where price is obliged to stop.
Where a wall comes from
Every listed option sits at a strike, and the open interest at that strike is a standing obligation for whoever is short it. Dealers are usually short what the public is long — calls above spot, puts below. Gamma measures how fast a position's delta changes as the index moves, so a strike carrying large open interest near the money generates the largest swings in what the dealer must hold to stay neutral. Aggregate that across the chain and the distribution is lumpy. The lumps are the walls.
The lumpiness is not random. Round numbers attract size, index overwriters sell calls at recurring distances above spot, funds buy puts below and monthly expiries concentrate open interest at a handful of strikes that then sit there for weeks. A wall is the visible residue of positioning put on for reasons that have nothing to do with today. It says business was done at that strike. It says nothing about who holds it now or why.
The regime decides the behavior
The same wall behaves in opposite directions depending on the sign of net gamma. When dealer gamma is positive, hedging leans against the tape: as the index approaches a heavy strike, the flow required to stay neutral works against the approach. Moves near it tend to slow and price can pin. When net gamma is negative the mechanics invert: hedging leans with the tape and the heavy strike becomes a place where flow feeds the move instead of absorbing it.
This is why a wall drawn on a chart without its regime is close to meaningless. The strike is the same number in both states. What changes is the direction of the obligation attached to it, and that is set by the sign of the aggregate estimate rather than by the size of the wall itself.
What a wall omits
A wall carries no timing. Open interest is a stock rather than a flow — it says how much is outstanding, not when any of it will be hedged or whether it already has been. It carries no direction: the same concentration sits there whether the index arrives from above or below. And it carries no certainty of magnitude, because every gamma figure anywhere rests on an assumption about which side of each contract the dealer holds. That assumption is a model, not a fact. Change it and the walls move.
How the desk reads it
On a working desk a wall is context for other work, not a signal on its own. The question it answers is narrow: does the level already under consideration sit inside a thick pocket of hedging obligation or in open air? The drawer lists the top call and put walls by strike for that reason. Walls also decay — open interest rolls, expiries pass, and yesterday's heaviest strike can be gone by the afternoon. The estimate is computed from the delayed SPX chain, which is a further reason to read the strike as a region rather than a line.
How it gets misread
The common misread is to treat a wall as support or resistance and trade the bounce. A wall is a concentration of obligation, not a floor. Traders park stops just beyond the biggest put strike, reasoning that price should hold there, then discover the regime was negative and the same open interest was pushing the index through. The second version is subtler: reading a wall that is heavy on paper but far enough from spot that the hedging attached to it is barely moving.
Where it lives
A wall means little on its own; these terms carry the rest of the context the drawer assumes.
THE DESK PUBLISHES THE NQ DEALING RANGE AT 22:03 ET, BEFORE THE SESSION — AND SCORES IT AFTER, EITHER WAY. SEE THE RECORD → · AUDIT THE CHAIN →