The option chain shows positioning strike by strike. Sometimes you do not need that detail, you need the summary: which side is writing more options right now, and is that changing? Combined OI answers it in one chart.
What is combined open interest?
Open interest is the number of option contracts that are open in the market. It rises when new contracts are created and falls when positions are squared off.
Combined OI aggregates that across every strike. All call OI is summed into Total Call OI, all put OI into Total Put OI, and both are plotted against the underlying's price through the day. The header shows the running totals so the balance is readable at a glance.
Which side is writing?
The reading rests on who sells options. Writers are typically the better capitalised, higher conviction participants, so the side they are selling indicates what they are positioned against.
As an analytical observation, and this is how the market generally reads the balance:
- Total Call OI above Total Put OI reflects heavier call writing, meaning sellers positioned against upside. A bearish undertone.
- Total Put OI above Total Call OI reflects heavier put writing, meaning confidence that the market holds. A bullish undertone.
This is the same balance that PCR expresses as a single number in the option chain. Combined OI shows it evolving through the session rather than as a snapshot.
The crossover
The notable moment on a Combined OI chart is a crossover, when one line overtakes the other. It marks a shift in which side is now dominant in writing.
A crossover is read as adding weight to what price is already doing, not as an independent indicator. A trend accompanied by a crossover in its favour has more positioning behind it than one without.
Confirmed moves and unsupported moves
The practical use of Combined OI is checking whether positioning agrees with price.
When price falls while Call OI builds and Put OI unwinds, writers are backing the direction of the move. The two are consistent.
When price falls while Call OI declines and Put OI builds, writers are positioned against the move rather than behind it. That inconsistency is what the widget makes visible, and it is the reason traders use combined OI as a check on breakouts and breakdowns rather than as a signal in itself.
The Combined OI cheat sheet
| What you see | What it indicates |
|---|---|
| Price falling, Call OI rising, Put OI falling | Bearish positioning consistent with the move |
| Price rising, Put OI rising, Call OI falling | Bullish positioning consistent with the move |
| Price falling, Call OI falling, Put OI rising | Positioning inconsistent with the move |
| Price rising with Call OI rising sharply | Writers positioning against the advance |
| A crossover between the two lines | Shift in which side is dominant |
| Both lines flat while price ranges | Little fresh positioning either way |
Using the widget
Switch instruments with one tap across the major indices, or use Search Scrips for stock F&O. Set the Duration, down to one minute granularity, to match your timeframe, and switch between Chart and Table views, lines for the shape and the table for exact figures. The header carries the running Put OI and Call OI totals, updating live through market hours.
A three step routine
Step 1. Read the header totals. Which side is larger frames the overall balance.
Step 2. Watch the slope of each line rather than only the level. The side adding OI fastest is the side currently pressing.
Step 3. Check for agreement. Price direction, OI direction and a crossover all pointing the same way describes a move with positioning behind it. When they diverge, the positioning does not support what price is doing.
Go deeper. Combined OI gives the market wide balance. The Open Interest widget shows which strikes hold the walls, the Option Chain adds premiums and Greeks, Multistrike OI tracks chosen strikes through the day, and Max Pain distils the same data into one expiry level.
