Positioning · Lesson 01 of 4 · Concept
Open interest
Open interest counts contracts currently outstanding, not contracts traded. It rises when a new position is opened and falls when one is closed. On NIFTY’s 22 September 2026 expiry the chain carried 165.9 million contracts of call open interest against 138.1 million of put.
NIFTY weekly expiry, 22 September 2026 · MarketCue one-minute option-chain capture
A stock, not a flow
Volume counts what changed hands during a session and resets each morning. Open interest counts what is still outstanding at the end of it and carries forward. One contract traded ten times between the same two participants adds ten to volume and nothing to open interest.
That makes open interest a record of commitment rather than activity. It rises only when a buyer and a seller are both opening, and falls only when both are closing; when one opens and the other closes, it does not move at all.
Heaviest call open interest on this chain sat at the 23,350 strike and heaviest put at 23,300, with the index closing between them at 23,329.
The four buildups, and their limits
Price and open interest are conventionally read together in four combinations: price up with open interest up is described as a long buildup, price down with open interest up as a short buildup, price up with open interest down as short covering, and price down with open interest down as long unwinding.
The labels are a convention rather than a measurement. Open interest is a net count and carries no record of who initiated a trade or why, so the same movement is consistent with several different sets of participants doing different things. Heavy volume against flat open interest, in particular, is contracts changing hands rather than positions being created — and no direction should be attributed to it.
MarketCue names where open interest sits and how it changed. It does not call a heavy strike support or resistance, because open interest records a position, not a commitment to defend a level.
Common questions
What is open interest in options?
The number of contracts still outstanding at a strike, as opposed to the number traded. It increases when new positions are opened and decreases when they are closed.
What is the difference between open interest and volume?
Volume counts contracts traded during a session and resets daily. Open interest counts contracts still open and carries over between sessions. High volume with unchanged open interest means positions changed hands rather than being created.
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Written and maintained by MarketCue research · Updated 9:30 AM IST · 23 October 2026
How these figures are produced
Every price on these pages was traded on the exchange and is read from our own option-chain capture, which records the NIFTY and SENSEX chains once a minute through the session. Each page names the session its figures come from.
Figures that a model produced rather than the market — the Greeks, implied volatility — are labelled as model outputs wherever they appear, and never presented beside traded prices without saying which is which. The pricing is checked against published reference values on every change.
Where our own data cannot support a claim, the page says so instead of generalising. MarketCue is not a registered investment adviser, research analyst or broker under SEBI regulations.