What Are Call and Put Walls? Options Walls Explained

A call wall or a put wall is the strike where one side of the listed options book carries its heaviest positioning, marking where dealer hedging concentrates. The word carries no view about direction. It names a price level where the mechanical flow from hedging is densest, and there is more than one way to measure which strike that is.

Wall charts are everywhere, and two of them can disagree about the same ticker on the same day without either being wrong. This page covers the two definitions in circulation, why the side a wall sits on is part of its meaning, why walls are read inside a band around the current price, the cases that look like rendering faults and are not, and what a wall cannot tell you. It is descriptive throughout.

Two definitions, and why a chart has to name one

The first definition is the largest per side dollar gamma at a strike. Gamma is how fast an option's delta changes as the underlying moves, so dollar gamma is a measure of how much hedging a one percent move forces at that strike. Kresmion's methodology computes it per strike as `gamma * open interest * 100 * spot^2 * 0.01`, which puts it in dollars of underlying per one percent move, computed for calls alone and for puts alone.

The second definition is the largest per side open interest at a strike, which is a raw count of contracts outstanding. It needs no pricing model, and it weights every contract the same whether it sits on top of spot or far from it.

The two picks are not interchangeable. They land on different strikes for the same name on the same session often enough to matter, and in Kresmion's own coverage that disagreement is concentrated on the put side, while the call side agrees far more often than the put side does. A chart that shows a wall without naming which quantity it ranked leaves the reader guessing what the line means.

One more detail separates a wall from something that looks like one. Both definitions have to be aggregated per side: calls only for the call wall, puts only for the put wall. A chart built on a dealer signed net series, calls minus puts at each strike, is a different object: taking a maximum off that net series answers a different question while occupying the same pixel.

A call wall counts above spot, a put wall below

A call wall is potential resistance at or above the market and a put wall is potential support at or below it, each side anchored at the listed strike nearest the current price. That is the whole content of the word, and it means the search for each wall belongs on its own side of spot.

Left unconstrained, the maximum answers a different question, "where is the most call gamma anywhere in the chain", and the answer can be nonsense as a level. A large put position sitting well above the current price is a real position, usually deep in the money, and it is never support. Built without that constraint, the same calculation puts put walls above spot and call walls below it, and occasionally inverts a pair outright. Constraining each wall to its own side moves those picks and costs almost nothing: measured across the stored history of names and dates, the constrained pick keeps nearly all of that gamma on average, and none of the healthy ones loses its wall.

The strike nearest the current price is eligible for both sides, and that detail is load bearing. A strict "at or below spot" cut for the put side looks equivalent and is not: when the heaviest put gamma sits a few cents above spot at the nearest listed strike, a strict cut throws away most of that side's gamma over a rounding distance.

The band around the current price, and what it leaves out

Walls are read inside a band around spot rather than across the whole chain. Kresmion uses plus or minus twenty percent of the current price, the same band its strike profile draws.

Far from spot, open interest stops being a statement about the present. Much of it is stale deep in the money positions left from older trades that nobody has closed, and that open interest can be larger than anything near the money. Ranking across the whole chain would hand the wall to those piles again and again, which is what the band exists to prevent, and why widening it to capture a large distant number defeats the purpose.

The two definitions behave differently at the edge of that band. Dollar gamma decays away from spot on its own, so a gamma wall peaks inside the window without any help. Open interest does not decay, so an out of the money open interest tail can still be rising where the window ends. When that happens the pick is a boundary rather than a peak, and an honest chart flags it as sitting at the edge of the window instead of presenting it as a level. Kresmion's open interest walls carry that flag for exactly this reason.

Cases that look like errors and are not

Both walls on the same strike. When the at the money strike carries the heaviest gamma on both the call side and the put side, the call wall and the put wall land on one number. It is the ordinary outcome when open interest clusters tightly around the current price, and a chart that does not say so reads as a rendering fault.

Wall distances that jump in large steps. Strikes are listed by the venue on a fixed grid, and on low priced names that grid is coarse relative to the price. On a stock near six dollars where the venue lists strikes fifty cents apart, one strike increment is more than eight percent of spot, so wall distances on such a name arrive in steps of roughly eight percent rather than in fine gradations. The rule cannot do better than the strikes the venue lists.

Blank walls. When a chain capture comes back with open interest blanked on nearly all of its contracts, there is no wall to compute, and the honest output is nothing rather than a strike ranked off a handful of surviving rows.

What a wall is not

A wall is not a floor and not a ceiling. Prices trade through walls routinely. What the level describes is where hedging flow is dense, and dense flow is a condition rather than a barrier: whether it leans against a move or pushes the move along depends on the sign of aggregate dealer gamma, which is the subject of dealer gamma exposure. Near a strike where dealers hold long gamma, the hedging is stabilizing and the strike can act like a magnet into an expiry. Where dealers are short gamma, hedging around the same concentration pushes the move further.

A wall is also a snapshot. Open interest changes every session, and it drops away when the expiry carrying it rolls off, so the strike holding the heaviest positioning today may hold nothing next week. If the terms call, put, strike, and open interest are new, what a call option and a put option are covers the vocabulary underneath all of this.

How Kresmion computes and shows walls

Kresmion computes modeled dealer greeks exposure nightly for a curated universe of US names from listed option open interest, using closed form Black-Scholes with its assumptions stated, and stores both wall definitions side by side rather than picking one and hiding the choice. The live SPY snapshot on this page prints the gamma pair, one call wall and one put wall with each tile naming the definition, next to the net gamma profile chart; the per side series the walls were ranked from stays internal. The full suite across every covered name, including the implied volatility tab, sits in Kresmion's greeks tool and opens with a free account.

Key takeaways

Frequently asked questions

Are call and put walls the same thing as support and resistance?

They are not the same measurement. Support and resistance are read from price history, while walls are read from options positioning and dealer hedging. A wall can coincide with a level that traded before, but it is derived from where contracts sit today, and it moves when that positioning moves.

Do walls predict where a price will stop?

No. A wall describes the backdrop: it says where hedging flow is concentrated right now, given the contracts currently open. Prices move through walls regularly, and the positioning that created the wall can be unwound or expire before the price ever gets there.

Why do two wall charts disagree about the same ticker?

Most often because they rank different quantities. One may be ranking per side dollar gamma and the other per side open interest, and those pick different strikes, especially on the put side. They can also differ in the band they search around spot, and in whether they aggregate per side or take a maximum off a dealer signed net series.

Can a call wall and a put wall sit on the same strike?

Yes, and it is common. It happens when the strike nearest the current price carries the heaviest gamma on both the call side and the put side, which is the usual shape for names whose open interest clusters around spot. The two walls landing on one number reflects that clustering rather than a fault in the chart.

This page is information, not investment advice.

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Source: closed form Black-Scholes greeks, with the modeling assumptions stated on Kresmion's greeks exposure tool; Kresmion modeled dealer positioning data computed from listed option open interest.

Kresmion Research.