The strike with the largest put exposure below the current price. It often acts as a floor because dealer hedging there tends to be buying.
What this wall is
The Put Wall (Put Wall) is the strike price with the biggest pile of open put contracts below the current price. A pile that large means a matching hedge held by market makers, so the level behaves as a real reaction zone, not a psychological line.
Why price reacts there
The sellers of those contracts (often market makers) hedge by selling the underlying as price approaches from above and buying it back as price moves away. Near the wall in a positive Gamma regime, their hedge is buying into the drop, so the wall acts as an absorbing cushion. That is why the Put Wall is described as the structural support of the range.
When it turns from a cushion into an open door
A clear close below the wall changes the equation: the restraining hedge unwinds, and a lot of positioning gets rolled to lower strikes, so the wall itself moves down. If the break also comes with a cross of the Gamma Flip, the decline feeds on selling hedges. The whole regime flipped, not just one level.
Hypothetical example
An index at 5,050 with its wall at 5,000 and a pile many times larger than its neighbors: down sessions slow near it and bounce off it repeatedly. A clear close below it, and the same zone becomes structural resistance in later bounces until positioning is rebuilt.
Common mistake
Treating the wall as a fixed magic line: it reflects positioning that changes daily and is redrawn after every expiration · read it fresh each morning; its source and date are part of reading it.
Where to see it on the platform
The Gamma dashboard shows the Put Wall for every covered ticker, updated through the session, alongside the Call Wall and the Gamma Flip, so the map of the structural range is complete.
