What are call walls and put walls?
The call wall is the strike with the largest concentration of call gamma; the put wall is its counterpart on the put side. They matter because they are the levels where options dealer hedging activity is most concentrated — the call wall commonly acts as resistance and a price magnet, and the put wall as a support zone. They are not lines someone drew on a chart; they are the visible footprint of the largest hedging obligations in the options market.
Why does the call wall act as resistance?
At a strike with heavy call gamma where dealers are long those calls, hedging is stabilizing: as price rises toward the strike, dealers sell stock against their growing long deltas, and as it falls away they buy. That sell-into-strength, buy-into-weakness flow both slows advances through the level and pulls price back toward it — resistance and magnet at once. The effect strengthens as expiration approaches and gamma at the strike peaks.
Why does the put wall act as support?
The same hedging arithmetic on the put side. Around a heavily-populated put strike, dealer hedge adjustments lean against further declines — buying as price falls toward the strike. The put wall often marks the lower edge of the expected range, though its support is conditional: in a forceful selloff that pushes the market deep into negative gamma, hedging flips from cushioning to amplifying, and a put wall can give way quickly. Which is why the wall’s location matters less than the positioning behind it.
How are call and put walls calculated?
Most platforms find the strikes with the largest open interest or largest gamma computed under a fixed assumption about who holds the contracts. That’s a reasonable first cut, but it misses the question that determines whether the wall actually holds: whose gamma is it? A strike where dealers carry the exposure produces real hedging flows; a strike where customers face customers produces none. SpotGamma’s SGOI estimates actual market-maker and buyside positioning per strike and per name, which is what separates a load-bearing wall from a pile of open interest. The hedging pressure around these levels is visible in real time in HIRO.
How do traders use call and put walls?
As range boundaries and reference levels: the zone between the put wall and call wall frames the expected range, wall migrations (the wall rolling to a higher or lower strike as positioning shifts) signal regime changes, and price interacting with a wall is read alongside the sign of dealer gamma — pinning behavior near walls in positive gamma, breakout risk when gamma is negative. See also: gamma exposure (GEX) explained and what is negative gamma.
Last updated: August 2026 — Published by SpotGamma. For how positioning platforms compare, see our gamma exposure tool comparison.