- A call wall is the strike above spot with the heaviest positive dealer gamma. Dealers there must sell into rallies approaching the strike, which caps price.
- A put wall is the strike below spot with the heaviest negative dealer gamma. Selloffs accelerate INTO it (short gamma), then react hard at the strike.
- Walls are dollar-sized. A $4B wall behaves nothing like a $0.4B wall at the same strike.
- Call-wall breaks tend to be orderly; put-wall breaks tend to be violent.
A call wall is the strike above spot where positive dealer gamma piles up. Because gamma is largest at at-the-money strikes with near-term expiries, and because dealers hedging long-gamma exposure must sell into rallies to stay flat, price approaching a call wall meets a mechanically-priced supply of futures selling. That selling grows every time price presses in, which is why walls are the strike level SPX and SPY commonly stall against.
As of the 4 Aug 2026 close, SPX's call wall sits at 7,750. A rally 1% into that strike meets a mechanically-priced supply of futures selling from dealers hedging their long-call positions. That is not a chart pattern; it is arithmetic.
Put walls: accelerate then react
A put wall is the negative-gamma twin below spot. Dealers there hold heavy short-put exposure, so their hedge is short underlying. As price drops toward the strike, gamma works against them; they have to sell into the drop to stay flat. That amplifies the selloff INTO the wall.
The reaction at the wall is where the mirror ends. At the strike, the short puts flip into deep-ITM territory. Dealer gamma there collapses, and the hedging that fueled the drop stops. If the reversal has legs, the book flips positive-gamma at that strike and dealers start buying dips. That is why put walls often show sharp reactions on the tape without providing much warning.
The asymmetry with call walls matters for position sizing. Call walls break orderly because the brake fades as calls move deep ITM. Put walls break violently because the accelerator often continues below the strike into the next put wall or the flip line. Widening stops or stepping aside is the honest read at a put-wall break.
Near wall vs global wall
The near wall is the heaviest strike close to spot in the visible band around price. The global wall is the heaviest strike anywhere below spot (put) or above spot (call), which can be much further away. On the dashboard, the Put Wall hero card shows the global put wall; the Combined view lists the near shelves and walls in order. When the two disagree, the near wall usually rules for the intraday tape while the global wall shapes the monthly-OPEX magnet.
What to watch after a wall break
When price breaks a call wall, watch the next refresh. If overnight open interest adds sit above the breach strike, the wall rolls higher and the break is a bullish continuation. If OI doesn't add, the break was a clean extension into thin book and the top may be close. Two different breaches with the same candle behave differently the next morning.
The one tell that a level is done working is a regime flip on the flip line. The one tell a level is about to matter more is OI adding at the strike between sessions. Both live on the dashboard.
Frequently asked
What is a call wall?
A call wall is the strike above spot with the heaviest positive dealer gamma. Dealers hedging those calls must sell into rallies approaching the strike, which mechanically caps price. Walls are dollar-sized: a $4B wall behaves differently from a $0.4B wall at the same strike level.
What is a put wall?
A put wall is the strike below spot with the heaviest negative dealer gamma. Selloffs often accelerate into a put wall because short gamma amplifies the drop, then react hard at the strike as dealer gamma collapses. Put-wall breaks are usually violent; call-wall breaks are usually orderly.
How do you trade around gamma walls?
On a long-gamma day, the trade is fade the walls: sell rallies into the call wall, buy dips at the put wall. On short-gamma days, trade with the move; expect walls to fail more often. The wall's dollar size and the regime state on the flip line determine whether the fade is durable.