Call wall and put floor, explained
The call wall is the strike carrying the largest call open interest; the put floor is its downside counterpart. They matter because of who is on the other side of those contracts.
Why a wall acts like resistance
Dealers short a large block of calls at one strike must hedge by holding shares. As price approaches that strike, the hedge is already largely in place, so further buying pressure meets supply from delta adjustments. The strike behaves like a soft ceiling.
Why a floor acts like support
The mirror image. Heavy put open interest below the price leaves dealers hedged short; as price falls toward the strike, their hedge adjustment becomes buying, which cushions the move.
When they break
These are crowd-positioning levels, not laws. A genuine catalyst — earnings, a rate decision, an unexpected filing — reprices the stock faster than positioning can hold it, and the wall gives way. The level then often flips role.
Using them well
Read them as where the crowd has money at risk, not as a forecast. They are most useful for framing a move that is already happening: knowing that price just cleared the call wall tells you something about who has to adjust next.