What is a call vs put OI chart?
Each option strike carries some number of open call contracts and open put contracts. A call vs put OI chart plots those two numbers side by side across strikes for one expiry, so you can see at a glance where positions are concentrated and how the balance shifts from calls to puts as you move through the strikes. The live Nifty chart adds open interest change, the put call ratio and the spot price, and can replay how the picture developed through the session.
The idea behind reading it is simple. Option writers tend to defend the strikes where they hold large positions, so those strikes can act as areas where price slows or reverses. That is a tendency, not a rule, and the sections below cover how to use it without over-reading it.
Four things to read on the chart
Call OI wall above spot
Possible resistanceThe strike above spot with the largest call open interest. Writers may defend it, so price often slows there, especially near expiry. Watch whether its open interest is growing or fading.
Put OI wall below spot
Possible supportThe strike below spot with the largest put open interest. It is commonly treated as a floor. Acceptance below it, on rising volume, marks a change in structure.
OI change
Where positions move nowNew open interest added or removed since the reference time. It shows which side is being built or unwound today, which the total cannot show on its own.
PE − CE difference and PCR
Balance by strikeThe balance of puts and calls at each strike and across the range. It makes it easy to spot where the positioning tips from calls to puts as you move through the strikes.
The corridor idea: the put OI wall below spot and the call OI wall above spot form a corridor. Price inside it is in the zone where positioning is most defended; price accepted beyond a wall means positioning has changed, and the move can extend.
Open interest vs open interest change
| Measure | Tells you | Best for |
|---|---|---|
| Open interest | Where positions have accumulated across the expiry. | Finding the main walls and the overall structure. |
| Change in OI | Where positions are being added or closed now. | Judging whether a wall is strengthening or fading. |
| Volume | Where trading activity happened today. | Separating real new positioning from intraday churn. |
A strike with large open interest that is shrinking is a weaker level than one with a smaller total that is still growing. When a wall gains open interest on rising volume, that is genuine new positioning; when volume spikes but open interest does not move, it was mostly churn.
How expiry reshapes the chart
The same chart reads differently as expiry approaches. Open interest at strikes that are unlikely to finish in the money falls away as writers close positions and premium decays. What remains concentrates near spot, which sharpens the support and resistance picture. Heavy unwinding on one side often means writers are booking profits, and price can gravitate toward the strike that still holds the most open interest. Weekly contracts compress this cycle into days, while longer-dated contracts tend to roll positions forward instead of closing them outright.
Compare with max pain on expiry day, and keep the concepts separate: max pain describes where writers collectively benefit most, while the OI walls describe where positions are concentrated. They can agree or disagree at any moment.
A simple reading routine
- Set the expiry and range. Choose the active expiry and a strike range around the at-the-money strike so the chart shows the strikes that matter.
- Mark the walls. Note the largest call open interest above spot and the largest put open interest below it.
- Check the change. See whether each wall is gaining or losing open interest, and whether the PCR is rising or falling.
- Watch the session trend. Use the replay to see how the walls formed rather than judging one frame.
- Confirm with price. Trust a level more when price has reacted to it before, and less when it has just appeared.
Limitations and common misreads
- Levels are zones, not walls. Momentum, news or a fall in a strike's open interest can carry price straight through.
- Both sides hold the position. Each contract has a buyer and a seller, so open interest cannot tell you who initiated it or why.
- Hedges and spreads add open interest. A protective put or a spread leg can build a “wall” without a directional view behind it.
- The total can hide the shape. Check the put call ratio alongside the strike-level chart, since the same aggregate can come from very different distributions.
- Stocks are thinner. Single-stock strikes with little open interest produce noisy levels; give them less weight.