The Put Wall is the strike with the largest net negative Gamma in the underlying stock/ETF.

Why does Put Wall matter?

It can act as support, indicating where buyers may enter the market.

How to use a Put Wall

The Put Wall level lets you know where support lies for a stock, and a change in the price of the Put Wall can help you can manage your risk while either long or short.  A shift higher is often a bullish signal while a shift lower in the Put Wall is a bearish signal.