An open interest screener answers one question for the whole F&O segment at once: where is option positioning moving most one way right now? OIData’s Trending OI Screener reads the option open interest of every F&O stock, over 200 of them, every 30 seconds while the market is open, and puts the stocks whose positioning has tilted furthest since the previous close at the top. This guide explains the two readings it shows, how its filters narrow the list, and what the readings can and cannot tell you.
What an open interest screener does
Open interest is the number of option contracts still open at a strike. When it rises, new positions are being written; when it falls, positions are being closed (what open interest is). Reading it one stock at a time on an option chain is slow: by the time you have checked ten stocks, the first one has moved on. An open interest screener does that reading for every stock in one table and puts the most one-sided stocks first.
OIData’s screener is built on Trending OI, the page that follows call and put open interest through the session for one index or stock. The screener applies the same two readings, Day Strength and Flow, to every F&O stock at the same moment.
Day Strength: puts against calls since the previous close
For each stock the screener adds up the change in call open interest and the change in put open interest since the previous session’s close, across the ten strikes either side of the stock’s price. Day Strength is the put change minus the call change, as a share of the open interest on those strikes.
Fresh put writing leans bullish and fresh call writing leans bearish (why the writers’ side matters), so a green +9% means puts have been added well ahead of calls, and a red −9% the reverse. The dots beside the number say how one-sided the change has been: one dot when 30% of the movement points one way, two from 40%, three from 60%. A large percentage with one dot means a lot moved on both sides; three dots means at least 60% of it went one way.
Flow: the last fifteen minutes
A build from the morning stays in the day’s numbers all afternoon, so Day Strength alone can’t say whether the pressure is still there. Flow reads only the last fifteen minutes, strike by strike, and shows how one-sided that quarter hour has been, with the same dots. A grey Quiet means too little open interest moved to score. Flow needs fifteen minutes of readings, so it fills in from about 09:30.
Unwind marks a stock whose calls and puts both shed open interest over those fifteen minutes. Positions are being closed, not built, so the build-up reading doesn’t apply until fresh positions appear again.
Reading the open interest screener on a real session
The table above is from 12:56 on Monday 19 October 2026. ICICIBANK leads with Day −21% and three dots: since Friday’s close, call open interest across its strikes had grown far faster than put open interest, and most of the movement pointed that way. Its Flow, though, read +51% with two dots: in the last fifteen minutes the balance had swung toward puts. CANBK showed the mirror image, Day +15% with three dots and Flow −50%. CROMPTON was the agreeing case, Day −14% and Flow −49%, both leaning bearish. FEDERALBNK and SRF carried the Unwind tag: both sides were shedding open interest in that quarter hour.
None of these is a forecast. The screener tells you where positioning is most one-sided right now; the price chart and the full Trending OI page tell you what to make of it.
Filters that narrow 200 stocks to a handful
- Direction keeps only the bullish or only the bearish Day readings.
- Dots set a minimum for Day and for Flow. A Flow minimum leaves out the stocks that are Quiet or still warming up.
- Flow agrees with Day keeps the stocks whose last fifteen minutes point the same way as their day so far, such as CROMPTON above, and drops the ICICIBANK kind.
- Search finds a stock by its symbol, and any column header sorts the table.
Clicking a stock opens its readings every three minutes since the open: the change in call and put open interest, Day Strength and Flow, newest first. From there, Open in Trending OI takes it to the full page, with the chart, your own choice of strikes and past sessions.
The strikes and the series an open interest screener should read
Every stock is read across the ten strikes either side of its price, so a large stock and a small one compare on the same footing, and far strikes where little trades can’t swamp the reading. The window moves only when the price travels more than two strikes from its centre, so the reading doesn’t jump every time the price crosses a strike.
Stock options on NSE expire on the last Tuesday of the month (SEBI’s circular of 26 May 2025 set one expiry weekday per exchange, and NSE chose Tuesday). In the last days before that expiry, positions roll to the next month, so from four days before a monthly expiry the screener reads the next month’s series. The line above the table always names the series being read.
How it fits with the other screeners
The Buildup Screener sorts each stock’s futures by price and open interest into long build-up, short build-up, short covering and long unwinding (what those four mean). The GEX Screener ranks stocks by option dealers’ gamma. The open interest screener sits between them: it reads the options’ own positioning, puts against calls, and how fresh that positioning is.
Common questions
Does a strong reading tell me what to trade? No. It is a reading of option positioning, not a forecast. It shows where open interest has moved most one way, so you know which stocks are worth a closer look; the decision needs price and the rest of the picture.
How fresh is this open interest screener? Every stock is read every 30 seconds while the market is open. After the close, the day’s final table stays up, with Flow left blank, until the next session.
Why can Day Strength here differ from the Trending OI page? The screener always counts from the previous session’s close, across ten strikes either side of the price. Trending OI counts from the first reading it holds for that stock that day, across the strikes you pick, so the two figures can differ.
A 3-minute video walks through the screener panel by panel, in English, Hindi, Tamil, Telugu, Kannada and Malayalam, on the Tutorials page. To try the open interest screener yourself, open the Trending OI Screener during market hours.