# Put Wall Source: SquawkFlow URL: https://squawkflow.com/glossary/put-wall Category: Options Positioning Published: 2026-09-21 Updated: 2026-09-22 Type: Definition > The strike below spot carrying the most put gamma, why the usual dealer-buying explanation for it is backwards, and what actually holds the level. --- ## What a put wall is A put wall is the strike below the current price where put open interest, weighted by gamma, is largest. It is a single number produced by a gamma exposure model, recomputed each session from the prior session's settled open interest, and it is read as the lower edge of the range the options market is currently positioned around. Most services describe it as support. It is not an observed trade, a resting order, or a level anyone has undertaken to defend, and nothing about it says price will stop there. SquawkFlow publishes the current SPX put wall free on the [SPX gamma exposure page](/gex). ## Two definitions that do not always agree Two constructions circulate. The stricter one ranks each strike by gamma multiplied by open interest. The looser one just takes the largest put open interest below spot. They frequently point at different strikes, because gamma weighting pulls the answer toward strikes nearer to spot. SquawkFlow uses the gamma-weighted form for both walls. When two services publish different put walls for the same day, that difference is usually the reason. ## Why the usual explanation is backwards The story repeated on most explainer pages runs: customers buy puts for protection, dealers take the other side and are short them, and as price falls toward the strike those dealers buy the underlying to stay delta neutral, putting a floor under the market. The first half is the standard convention. The SqueezeMetrics [gamma exposure white paper](https://squeezemetrics.com/monitor/download/pdf/white_paper.pdf) states it as an assumption: "Put options are bought by investors; sold by market-makers." The hedging direction is the part that does not follow. A short put carries positive delta, and as spot falls that delta becomes more positive, so a delta-neutral desk short puts **sells** the underlying into the decline and sells more the further it goes. The Options Industry Council gives the general rule in its [gamma primer](https://www.optionseducation.org/advancedconcepts/gamma): "Long options, either calls or puts, always yield positive Gamma. Short calls and short puts will have negative Gamma." That is amplification, not support. For a put wall to generate genuine dip buying through delta hedging, the desk has to be long the puts, which is the opposite of the assumption the calculation is built on. ## What does hold the level Several mechanisms survive that check, and none of them is first-order delta hedging on short puts. Below the strike those puts go deep in the money, delta saturates and gamma collapses, so the selling that was running all the way down simply stops, which on a chart is hard to distinguish from a bid appearing. Holders who bought protection out of the money may take it off once spot reaches the strike, and when they sell the put back, the dealer closing that short position buys back the index it had sold against it. The buying comes from the unwind, not from the option running out of convexity: a put that started out of the money is at the money when spot arrives at its strike, which is where its gamma is largest, not spent. When a test fails and implied volatility comes back in, put deltas shrink and dealers buy back part of the hedge, which is a vanna effect rather than a delta one. And a put wall usually sits well below spot, so a level several percent away goes untested on most days for reasons having nothing to do with options positioning. That last point is why we publish no hold rate for the put wall. The one shown until August 2026 was withdrawn because it counted untested days as holds, and we have not replaced it with a figure we would stand behind. ## Put wall and call wall The [call wall](/glossary/call-wall) is the same construction above spot, ranked on call gamma, and the pair is usually drawn as the two edges of a range. They are not symmetrical. The call wall story needs the dealer long the calls, the put wall story as usually told needs the dealer long the puts, and the standard convention grants only the first. [Call wall and put wall compared](/learn/call-wall-put-wall-explained) derives both sides and covers what a break of each one tells you. A put wall break is the more informative of the two, particularly when price is also below the [zero gamma](/glossary/zero-gamma) level, where modelled hedging amplifies moves rather than damping them. ## What SquawkFlow publishes The SPX put wall on [our free gamma page](/gex) comes from a full-chain morning snapshot built from Cboe settlement open interest, re-pricing 19,544 SPX contracts on 2026-09-22. That count moves with the listed chain rather than being fixed. The input settles overnight, so the wall is fixed for the session while spot, the implied range and the 0DTE magnet refresh through it. *Educational content, not financial advice. See our [risk disclosure](/risk-disclosure).* --- ## Citation Source: SquawkFlow, https://squawkflow.com/glossary/put-wall Retrieved: 2026-09-25 09:35 ET Attribution: cite the page URL rather than a copied number. Levels are recomputed every session, so a number without its date is wrong within a day. SquawkFlow publishes market-structure data and education. Nothing here is investment advice, a price target or a recommendation, and we have no order execution.