Support/Resistance (OI Walls)

In options trading, support and resistance levels emerge from concentrated open interest at specific strike prices — often called "OI walls." A large put wall (high put open interest at a strike) has acted as support, and a large call wall as resistance. The usual explanation is hedging flow around the cluster — buying into declines near a put wall, selling into rallies near a call wall — though open interest is unsigned, so who holds which side is an inference, not an observation.

OI walls are dynamic and change as traders open and close positions. The strongest walls form at round-number strikes (like $100, $150, $200) where open interest naturally concentrates. During options expiration, these levels become even more magnetic as gamma increases. The distance between the major put wall and call wall defines the expected trading range for the near term.

Options Pilot's Sentiment pillar identifies the major put and call walls in its Level 2 analysis, showing the specific strike prices and OI concentration. When the stock is trading between two strong walls, it suggests range-bound behavior that favors selling strategies. When the stock breaks through an OI wall, the move has tended to accelerate, creating a momentum signal.