# F&O derivatives scanners for NSE > Open interest screeners for NSE F&O stocks. Long and short buildups, futures premium and discount, put-call ratio extremes: positioning the cash tape cannot show. Canonical: https://dev.patternsradar.com/scans/derivatives Price tells you what happened. Open interest tells you who is committed to it. Every futures contract is a long and a short who both posted margin, so the direction OI moves alongside price sorts each session into one of four states: long buildup, short buildup, short covering, long unwinding. The four scans at the top of this page are that grid. Around them sit the other positioning reads. The basis is the leveraged market's opinion of the cash price, quoted as a premium or a discount. The put-call ratio marks crowding at its extremes. Futures volume against its own norm is the volume shocker, read from the derivatives desk. Two limits worth stating. Only the roughly 200 stocks with listed futures carry any of this data, which is what `from fno` in each query means, and open interest is counted in contracts summed across expiries because that is the unit NSE publishes. Expiry week bends every number here: OI falls mechanically as contracts settle, and the basis converges to zero by construction. ## The scans (11) ### Long buildup https://dev.patternsradar.com/screener/long-buildup.md ```sift from fno where fut_oi_change_pct > 3 and change > 1 ``` Futures open interest up more than 3% on a day price rose over 1%. New longs being opened. When a stock rises while its futures open interest grows, new money is being committed to the upside. Every added contract is a fresh long meeting a fresh short at a higher price, and price advancing tells you which side is paying up. The same move on falling OI would be short covering, a position being exited rather than conviction. A price-only screener cannot see the difference. Top 500 by turnover. ### Short buildup https://dev.patternsradar.com/screener/short-buildup.md ```sift from fno where fut_oi_change_pct > 3 and change < -1 ``` Open interest up more than 3% into a falling price. Fresh shorts being written. A falling price with growing futures open interest means the decline is being sold into rather than simply abandoned. Someone is opening new short positions at each lower level and paying margin to hold them. It is the bearish mirror of the long buildup, and it reads as a warning on longs you hold as much as a candidate list for shorts. Top 500 by turnover. ### Short covering rally https://dev.patternsradar.com/screener/short-covering.md ```sift from fno where fut_oi_change_pct < -3 and change > 1 ``` Price up while open interest drains away. Shorts buying themselves out. A rally on falling open interest is positions closing. Shorts buying back their contracts push price up without any new money committing to the upside. These moves can be fast, because a squeeze is forced buying, and they end when the covering does. Read the setup as a caution on chasing strength. Top 500 by turnover. ### Long unwinding https://dev.patternsradar.com/screener/long-unwinding.md ```sift from fno where fut_oi_change_pct < -2 and change < -0.5 ``` Open interest down more than 2% on a softer price. A trend losing its sponsors. Price easing lower while open interest shrinks means longs are leaving and shorts are not replacing them. An orderly exit rather than an attack. The thresholds here are looser than the buildup scans on purpose, because unwinding is gradual by nature, a position book trimmed over days, and waiting for a dramatic print would miss most of it. Top 500 by turnover. ### Open interest at a 3-month high https://dev.patternsradar.com/screener/open-interest-high.md ```sift from fno where fut_oi is highest in 3mo ``` More futures contracts open than on any day in three months. Record open interest means record disagreement. Every contract is a long and a short who both think they are right, and a three-month high in contracts outstanding marks the stocks where that argument is largest. On its own it says nothing about direction, so read the price trend alongside it. The resolution of a crowded position book is rarely quiet. Top 500 by turnover. ### Futures at a premium https://dev.patternsradar.com/screener/futures-premium.md ```sift from fno where fut_basis_pct > 0.5 and close > sma(50) ``` The front-month future paying more than half a percent over cash, in a stock above its 50-day average. The basis is the futures market's opinion of the cash price. A persistent premium means leveraged traders are paying a carry cost to be long, and they only do that willingly when they expect the move to continue. The trend filter matters here. A fat premium in a falling stock is stale hope; the same premium above a rising 50-day average is conviction with the trend at its back. Top 500 by turnover. ### Futures at a discount https://dev.patternsradar.com/screener/futures-discount.md ```sift from fno where fut_basis_pct < -0.2 ``` The front-month future trading at least 0.2% under cash. Hedging pressure, or supply the market expects. A future below cash means someone is willing to sell forward cheaper than today's price. Usually that is holders hedging a position they cannot or will not sell, and sometimes it is the market pricing in expected supply. Persistent discounts cluster in stocks under distribution. One caveat: the reading resets near expiry, when the basis converges to zero by construction, so treat expiry-week prints with suspicion. Top 500 by turnover. ### Put writers underneath https://dev.patternsradar.com/screener/put-support.md ```sift from fno where pcr_oi > 0.8 and close > sma(50) ``` Put-call open interest ratio above 0.8 in a stock above its 50-day. Put writers are paid to defend the strikes below. A put-call ratio above 0.8 means put open interest rivals call open interest, and most of that put OI is written rather than bought. Sellers collecting premium now have a financial interest in the stock staying above their strikes. In an uptrend that behaves like a floor being defended. The same ratio in a downtrend is panic hedging, which reads very differently, and that is why the trend filter is not optional. Top 500 by turnover. ### Call-heavy positioning https://dev.patternsradar.com/screener/call-heavy.md ```sift from fno where pcr_oi < 0.4 ``` Put-call open interest ratio under 0.4. Optimism crowded enough to be worth distrusting. A put-call ratio this low means the option book is almost all calls. The upside is crowded and the downside unhedged. Sometimes that is early conviction in a genuine move. At least as often it is late enthusiasm and the fuel for a stall, since heavy call writing above the price gives sellers levels to defend from the other side. A positioning extreme is a condition to notice, and it does not point in a direction on its own. Top 500 by turnover. ### Futures volume surge https://dev.patternsradar.com/screener/futures-volume-surge.md ```sift from fno where fut_volume > 1.5x avg(fut_volume, 20) ``` Futures volume at 1.5 times its own 20-day average. The volume shocker read from the derivatives market instead of the cash one. Futures volume is where positioning changes hands fastest, and a surge against the stock's own norm means the leveraged money found a reason today: news, a level, a rotation. Pair the list with the OI change to tell an entry from an exit. Surging volume with rising OI is positions opening. With falling OI it is an unwind. Top 500 by turnover. ### Put-heavy options flow https://dev.patternsradar.com/screener/put-heavy-flow.md ```sift from fno where pcr_vol > 0.7 ``` Put volume above 0.7 times call volume on the session. The traded-volume cousin of the open-interest PCR scans. Open interest measures positions being held; volume measures what changed hands today. On NSE single stocks the flow skews heavily to calls, with the median name trading roughly two calls for every put, so a session at 0.7 puts per call is a genuine tilt toward the downside and not neutrality. What volume cannot tell you is who. A put buyer hedging and a put writer harvesting premium print the same contract. Read it with the price: put-heavy flow in a falling stock is protection being bought, while in a rising one it is often writers funding the floor. Top 500 by turnover. ## Common questions ### What is a long buildup? Rising price with rising futures open interest. New contracts are being opened while price advances, so fresh money is committing to the upside. Compare short covering, where price rises because existing shorts are buying back and OI falls. ### What does the put-call ratio tell you? How the option book is positioned. A high PCR means put open interest rivals calls, often put writers collecting premium who then defend the strikes below. A very low PCR means the book is almost all calls, which is crowded optimism with little hedging underneath. Extremes on either side are conditions to notice. ### Why is open interest in contracts rather than shares? Because contracts are what NSE publishes, before and after a lot-size revision. Converting to shares needs the historical lot size of every contract, and that is not knowable for the older data. So the unit here is the exchange's own, and comparisons are made against a stock's own history, where the unit cancels out. ## More scan categories - [Breakout stock scanners for NSE](https://dev.patternsradar.com/scans/breakouts.md) - [Reversal stock scanners for NSE](https://dev.patternsradar.com/scans/reversals.md) - [Momentum stock scanners for NSE](https://dev.patternsradar.com/scans/momentum.md) - [Delivery percentage scanners for NSE](https://dev.patternsradar.com/scans/delivery.md) - [Volatility stock scanners for NSE](https://dev.patternsradar.com/scans/volatility.md) - [Candlestick pattern scanners for NSE](https://dev.patternsradar.com/scans/candlestick-patterns.md) - [Fundamental stock scanners for NSE](https://dev.patternsradar.com/scans/fundamentals.md) The whole library: https://dev.patternsradar.com/scans.md. --- Price and delivery data from the [eod2](https://github.com/BennyThadikaran/eod2) dataset: National Stock Exchange of India end-of-day files, split- and bonus-adjusted, updated after each close. 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