# 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 data the cash tape cannot show. Canonical: https://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 every session into one of four states — long buildup, short buildup, short covering, long unwinding — and the four scans at the top of this page are exactly that grid. Around them sit the other positioning reads: the basis, which is the leveraged market's opinion of the cash price expressed as a premium or discount; the put-call ratio, where extremes mark crowding worth distrusting; and futures volume against its own norm, which is the volume shocker read from the derivatives desk. Two honest limits. Only the roughly 200 stocks with listed futures carry this data — `from fno` in each scan makes that explicit — and open interest is counted in contracts, summed across expiries, because that is the unit NSE publishes. Expiry week bends every one of these numbers: OI drops mechanically as contracts settle, and the basis converges to zero by construction. ## The scans (11) ### Long buildup https://patternsradar.com/screener/long-buildup.md ```sift from fno where fut_oi_change_pct > 3 and change > 1 ``` Price and futures open interest rising together — fresh long positions being built, not shorts giving up. 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 — position exit, not conviction. The distinction is exactly what a price-only screener cannot see. ### Short buildup https://patternsradar.com/screener/short-buildup.md ```sift from fno where fut_oi_change_pct > 3 and change < -1 ``` Open interest rising into a falling price — fresh shorts being written with conviction. A falling price with growing futures open interest means the decline is being sold into, not just 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. ### Short covering rally https://patternsradar.com/screener/short-covering.md ```sift from fno where fut_oi_change_pct < -3 and change > 1 ``` Price up while open interest drains — shorts buying back, not buyers arriving. 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 — a squeeze is forced buying — but they end when the covering does, which is why the setup is read as a caution on chasing strength rather than an endorsement of it. ### Long unwinding https://patternsradar.com/screener/long-unwinding.md ```sift from fno where fut_oi_change_pct < -2 and change < -0.5 ``` Longs closing out into a drifting price — a trend quietly losing its sponsors. Price easing lower while open interest shrinks means longs are leaving without shorts replacing them — an orderly exit rather than an attack. The thresholds here are looser than the buildup scans on purpose: unwinding is gradual by nature, a position book being trimmed over days, and waiting for a dramatic print would miss most of it. ### Open interest at a 3-month high https://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 — maximum positioning, whichever side it favours. 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. It says nothing about direction on its own — read the price trend alongside it — but the resolution of a crowded position book is rarely quiet. ### Futures at a premium https://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 an uptrend — leverage leaning long. 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, which they only do willingly when they expect the move to continue. The trend filter matters: a fat premium in a falling stock is stale hope, while the same premium above a rising 50-day average is conviction with the trend at its back. ### Futures at a discount https://patternsradar.com/screener/futures-discount.md ```sift from fno where fut_basis_pct < -0.2 ``` The front-month future trading below the cash price — hedging pressure, or supply the market expects. A future below cash means someone is willing to sell forward cheaper than today's price — usually holders hedging a position they cannot or will not sell, sometimes the market pricing in expected supply. Persistent discounts cluster in stocks under distribution. The reading resets near expiry, when the basis converges to zero by construction, so treat expiry-week prints with suspicion. ### Put writers underneath https://patternsradar.com/screener/put-support.md ```sift from fno where pcr_oi > 0.8 and close > sma(50) ``` Heavy put open interest under an uptrend — option sellers paid to defend the levels below. A put-call ratio above 0.8 means put open interest rivals call open interest, and most of that put OI is written, not bought: sellers collecting premium who 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 reads very differently — panic hedging — which is why the trend filter is not optional. ### Call-heavy positioning https://patternsradar.com/screener/call-heavy.md ```sift from fno where pcr_oi < 0.4 ``` Call open interest dwarfing puts — 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, the downside unhedged. Sometimes that is early conviction in a genuine move; at least as often it is late enthusiasm — 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, not a direction to trade blindly. ### Futures volume surge https://patternsradar.com/screener/futures-volume-surge.md ```sift from fno where fut_volume > 1.5x avg(fut_volume, 20) ``` Futures trading at 1.5× their own 20-day average — the leveraged desk suddenly interested. This is 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 entry from exit: surging volume with rising OI is positions opening, with falling OI it is an unwind. ### Put-heavy options flow https://patternsradar.com/screener/put-heavy-flow.md ```sift from fno where pcr_vol > 0.7 ``` Put volume above 0.7× call volume on the session — hedging or fear running through today's options tape. This is 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 — the median name trades roughly two calls for every put — so a session at 0.7 puts per call is a genuine tilt toward the downside, 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. ## Common questions ### What is a long buildup? A rising price with rising futures open interest. New contracts are being opened while price advances, which means fresh money is committing to the upside — as opposed to 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: crowded optimism with little hedging underneath. Extremes on either side are conditions to notice, not directions to trade blindly. ### Why is open interest in contracts rather than shares? Because contracts are what NSE publishes, both before and after a lot-size revision. Converting to shares would require the historical lot size of every contract, which is not knowable for the older data — so the honest unit is the exchange's own, and comparisons are made against a stock's own history where the unit cancels out.