Call walls and put walls: where options positioning sits

Open interest is the number of option contracts still open at each strike. When one strike holds far more calls (or puts) than the strikes around it, traders call it a wall.

The dealers who sold those options usually hedge them by trading the stock. Near a large call strike, hedging can mean selling as price rises and buying as it falls — which tends to pin price near the strike, especially in the last days before expiration. A put wall below can work the same way from the other side.

So the call wall often reads as resistance, the put wall as support, and the space between as the range the options market is leaning toward for that expiration.

Before a report, the expected move — roughly the price of the at-the-money straddle — tells you how far the options market thinks the stock could travel. Comparing the walls to that range is useful: walls inside the expected move are likely to be tested; walls far outside it matter less.

After the report, positioning resets. The old walls can disappear within a session as traders close and roll, so a wall from the day before earnings is weak evidence the day after.

• Open interest doesn’t say who is long or short — a big call position can be bought calls or sold calls.
• Walls matter most close to expiration and in liquid names; in quiet stocks they can mean little.
• News beats positioning. A surprise moves the stock first; the walls catch up later.