Learn · options market structure
Call wall vs put wall: what's the difference?
The call wall is the strike above the current price with the most call open interest, and the put wall is the strike below with the most put open interest. In positive dealer gamma, the call wall often acts as resistance and the put wall as support. Both move as open interest changes.
Dealers amplify moves: trending and higher intraday volatility.
Why calls above and puts below
Most call open interest sits at strikes above price and most put open interest below, so the largest of each usually brackets the price.
When they matter most
Near expirations with large open interest, and in positive gamma, when hedging leans against moves. A decisive break through either wall in negative gamma can extend the move.
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