LEARN — STRUCTURAL LEVELS
Call walls and put walls are the strike prices where the largest concentrations of dealer gamma exposure sit. They represent levels where mechanical hedging flow is estimated to be heaviest — and they often act as structural support and resistance.
A call wall is the strike price above the current spot price where the largest concentration of positive gamma exposure sits. It represents a level where an unusually large number of call option contracts are open — and where dealer hedging activity is estimated to be heaviest if price approaches from below.
When price rises toward the call wall, dealers who are long gamma at that strike are estimated to sell shares to stay hedged. This selling pressure can make it structurally difficult for price to break through. The call wall acts as estimated resistance — not because of chart patterns or technical analysis, but because of mechanical hedging obligations.
A put wall is the strike price below the current spot price with the largest positive gamma concentration. When price falls toward the put wall, dealers are estimated to buy shares to stay hedged. This buying pressure can provide structural support.
The put wall acts as an estimated floor — a level where mechanical buying from dealer hedging may absorb selling pressure and slow or stop a decline.
When a wall is breached, something important can happen: the hedging activity that was resisting the move may reverse and accelerate it. If price pushes through a call wall and dealers become short gamma at those strikes, they may need to buy into the rally instead of selling — turning the former resistance into fuel for further upside.
This is why wall breaches are often associated with fast, directional moves. The structural force that was containing price suddenly switches direction.
Open interest concentration — more contracts at a strike means more estimated hedging activity. A call wall with 50,000 open contracts carries more structural weight than one with 5,000.
Proximity to expiration — gamma increases as options approach expiration. A wall driven by options expiring this week has more immediate hedging impact than one driven by options expiring in three months.
Relative size — a wall is only meaningful relative to the surrounding positioning. A strike with 10,000 contracts is a wall if surrounding strikes have 2,000. It is not a wall if surrounding strikes also have 10,000.
Call walls and put walls are not static. They shift as open interest changes — as new options are opened, existing positions are closed, and contracts expire. A wall that exists at Monday's open may have moved by Tuesday. Gamma Sonar recomputes wall levels from live data throughout the session — every 60 seconds on SPX, SPY, QQQ, and major indices, and every 5 minutes across 90+ additional tickers.
Gamma Sonar recomputes GEX from live greeks every 60 seconds on SPX, SPY, QQQ, and major indices — plus 90+ additional tickers on 5-minute cycles.
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