Open interest by strike, drawn as two bars: total call open interest and total put open interest, side by side at every strike on the same scale. Pairing them at the strike is what the view adds. An option chain holds the same two numbers in separate columns, so the comparison that matters, which side is heavier at this level, has to be done arithmetically. Here it is a difference in bar length.
Where those bars are tallest is where the most contracts have been written, and the writers of them have a direct financial interest in the underlying not settling past that level. That is the entire basis for reading heavy call open interest above the spot as resistance and heavy put open interest below it as support. The effect is real and it is soft: the walls hold in quiet markets and are cut straight through on news. They describe where the market has positioned itself, not where it is obliged to go.
Height alone is the less useful half of the chart. Watch what the bars are doing. A bar growing through the session is fresh writing arriving at that strike. A tall bar shrinking is the wall being dismantled, and a wall being dismantled has already stopped being a wall: the participants with the strongest interest in that level holding have chosen to stop defending it, which frequently precedes the underlying trading through. The static picture tells you where the market was. The change tells you what it is doing now.
Four of them matter:
The profile is at its most informative in the last sessions before expiry, when pinning around heavily written strikes is strongest. It is free, needs no account, and is analytics rather than advice.
Look for the strikes where open interest is concentrated. Heavy call open interest above the spot price is conventionally read as resistance and heavy put open interest below it as support, because the writers at those strikes lose if the underlying settles past them. The paired bars make those levels visible without comparing numbers column by column.
No. It tends to in quiet markets and it fails on news, when the level is simply traded through. It is a positioning observation rather than a barrier, and a strike whose call OI is falling has already lost whatever holding power it had, even though its bar may still be the tallest on the chart.
Positions at that strike are being closed, either by writers buying back or by holders squaring off. When a heavily written strike unwinds, the participants with the strongest interest in the price staying below it have stepped away, and the underlying moving through that level afterwards is common. It is one of the few readings here that is more useful than the bar height itself.
That is the conventional reading, on the logic that call writers expect the underlying to stay below their strikes. It is weak as a standalone signal, because the same bar can be a naked short, a covered call against stock, or one leg of a spread, and those carry very different intent. Read the imbalance alongside the change in open interest rather than on its own.
Analytics only. Not investment advice. Last updated .