How do I read the OI heatmap?
Read it in two directions. Scanning down a single time column shows how open interest is distributed across strikes at that moment. Scanning across a single strike row shows whether that strike is filling up or emptying out over time. The strongest reads come from rows that darken steadily while spot approaches them.
Does high open interest at a strike act as support or resistance?
High open interest marks where positioning is concentrated, and those strikes often behave as reference levels — heavy call open interest above spot is commonly read as resistance and heavy put open interest below spot as support. This is a crowding observation, not a rule. Levels can and do break, usually when that open interest unwinds quickly.
What does a band of open interest migrating upward or downward mean?
Migration means the crowd is repositioning rather than defending. When the heavy call band shifts to higher strikes through the session, positions at the old level are being closed and rebuilt further away, which usually follows a move that broke through it. The direction of migration frequently confirms a trend that price alone shows ambiguously.
What is open interest in options?
Open interest is the total number of option contracts in a strike that are still open and not yet squared off or settled. It counts positions, not trades. Rising open interest means fresh contracts are being created and new money is entering that strike; falling open interest means existing positions are being closed out.
Does the heatmap show total open interest or change in open interest?
Both views are available, and they answer different questions. Total open interest shows the standing book and highlights durable levels built over days. Change in open interest highlights only fresh activity and reacts much faster, which makes it the better view for reading what is being added or abandoned right now.
