Open interest
Open interest is the total number of futures and options contracts on a particular instrument that remain open at a given moment, meaning neither the buyer nor the seller has squared off the position, and the contract has not yet expired or been settled. It is reported by the National Stock Exchange and the Multi Commodity Exchange for every contract they list, and it is the single most-watched gauge of how much live money sits in a derivative.
Every open contract has two sides. When a fresh buyer and a fresh seller meet and create a new contract, open interest goes up by one. When both of them later close, it goes down by one. That two-sided arithmetic is what separates open interest from trading volume, and it is the reason a trader can read conviction from OI that price and volume alone do not reveal.
This article defines open interest precisely, separates it from volume, walks the price-versus-OI build-up matrix that Zerodha Varsity teaches, and shows where Kite surfaces OI in the option chain and on charts. For the day-to-day reading of how OI shifts, see the companion article on change in open interest .
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How open interest is created and destroyed
Open interest changes only when a contract is opened or closed, never when an existing contract simply changes hands. Four transaction types decide whether OI moves, and in which direction.
A fresh buyer trading with a fresh seller adds one to open interest. Both are taking new positions, so a brand-new contract exists where none did before. A buyer closing trading with a seller closing subtracts one, because the contract both held is now extinguished. The two middle cases leave OI flat: a fresh buyer trading with an existing long who is selling out, or a fresh seller trading with an existing short who is buying back, simply transfers an existing contract from one holder to another. The contract count does not change.
Put plainly, OI rises only when new money enters on both sides, and falls only when money leaves on both sides. This is why a busy session with heavy turnover can end with open interest barely moved: most of that turnover was position transfer, not position creation.
Consider a single Nifty 50 futures contract. On the day it first trades, one buyer and one seller create it, so OI is 1. If that buyer sells to a third party the next day, the original buyer exits and the third party enters; the contract still exists, so OI stays at 1. Only when a holder squares off against the opposite holder closing does OI fall back to 0.
Open interest versus volume
The most common confusion in derivatives is treating volume and open interest as the same thing. They measure different quantities over different time horizons.
Volume is a flow. It counts every contract traded during the session, and it resets to zero at the start of the next day. A single contract bought at 10 am and sold at 2 pm adds 2 to that day’s volume, even though no new position was created. High volume tells you the contract was actively traded; it says nothing about how many positions remain open at the close.
Open interest is a stock. It is the running level of contracts that are still live, and it carries from one session into the next without resetting. A contract that opens on Monday and is held to expiry on Thursday contributes to open interest every day in between, but only adds to volume on the two days it is actually traded.
| Property | Volume | Open interest |
|---|---|---|
| What it counts | Contracts traded in the session | Contracts still open at the moment |
| Reset | Resets to zero each trading day | Carries across sessions until contracts close |
| Created by | Any trade, including position transfers | Only fresh positions on both sides |
| Tells you | How actively the contract traded | How much live commitment exists |
| Where on Kite | Volume column and chart study | OI column in the option chain and chart study |
The practical upshot: a price move backed by rising open interest carries more weight than the same move on volume alone, because rising OI means new positions are being committed in the direction of the move, not just existing ones being shuffled.
The price-versus-OI build-up matrix
Zerodha Varsity frames open interest through a four-quadrant matrix that pairs the direction of price with the direction of open interest. The matrix is built around the futures contract, where the reading is cleanest, and it is the working tool most Indian intraday traders use.
| Price | Open interest | Interpretation |
|---|---|---|
| Up | Up | Long build-up |
| Down | Up | Short build-up |
| Up | Down | Short covering |
| Down | Down | Long unwinding |
A long build-up is price rising while OI rises. Fresh buyers are entering and pushing price up, and the rising OI confirms new money is funding the move, so the up-move has conviction behind it. A short build-up is price falling while OI rises: fresh sellers are entering, new bearish positions are being created, and the fall has commitment behind it.
The two falling-OI cases are exits, not fresh commitment. Short covering is price rising while OI falls. Existing short sellers are buying back to close, and their buying lifts price even as the contract count shrinks. The move up is real but it is being driven by sellers leaving, not buyers arriving, so it can fade once the covering is done. Long unwinding is price falling while OI falls: existing longs are selling out, their selling drops price, and again the move is an exit rather than fresh conviction.
Reading the quadrant tells you whether a move is fuelled by new positioning, which tends to persist, or by position closing, which tends to exhaust. A breakout on a long build-up is sturdier than the same breakout on short covering. Varsity’s own caution is worth keeping: this matrix is framed for the stock or index futures contract, and applying the same long-build-up or short-build-up labels to a specific option strike needs more care, because option open interest behaves differently across strikes.
The three-dimensional view: price, volume, open interest
Open interest works best alongside price and volume, not instead of them. The standard framing treats the three as separate dimensions of the same move. Price shows direction. Volume shows intensity, how much trading happened. Open interest shows conviction, how much of that trading created lasting positions.
A breakout that comes with both rising volume and rising open interest is the strongest signal the three can give together: the move has direction, it traded heavily, and it left new committed positions behind. A breakout on rising volume but flat or falling OI is weaker, because the heavy trading was mostly position transfer, not fresh commitment. Combining the three is how traders separate a genuine trend from a false move that looks active but leaves no new money behind.
Lot size, contracts, and the share-equivalent figure
Open interest is fundamentally a count of contracts, but NSE frequently presents it as a share-equivalent. To convert, multiply the contract count by the lot size of that instrument. If Nifty futures show OI of 2,00,000 contracts and the Nifty lot is 75, the share-equivalent OI is 1,50,00,000 units of the underlying. Both numbers describe the same positions; one is in contracts and the other in the notional underlying.
This matters because the index-derivatives reforms that took effect from late 2024 raised contract notional values to roughly the Rs 15 lakh to Rs 20 lakh band, so the same rupee exposure now sits in fewer contracts than before. When comparing OI across periods, check whether the lot size or the contract specification changed in between, or you will misread a specification change as a position shift.
Market-wide open interest and the F&O ban
Open interest also drives the F&O ban mechanism. NSE tracks market-wide open interest in each stock against a market-wide position limit. When the aggregate OI in a scrip’s derivatives crosses 95 per cent of that market-wide limit, the scrip enters a ban period, during which only position-reducing (offsetting) trades are allowed and fresh positions attract a penalty. This is the clearest case where the absolute level of open interest, not just its direction, carries a hard regulatory consequence. For the trigger mechanics and the penalty structure, see why scrips enter the F&O ban .
Because derivative contracts are created by agreement between a buyer and a seller rather than drawn from a company’s share count, open interest in a stock’s futures and options can exceed its free-float share count. The market-wide position limit is what caps that build-up before it becomes systemically large.
Where Kite displays open interest
Kite surfaces open interest in two places. In the option chain , each call and put strike carries a current OI column, alongside the change-in-OI column that most traders read together with it. The chain gives a snapshot of where positioning is concentrated across strikes for a chosen expiry.
On Kite charts, Zerodha added open interest as a plottable study in 2020, so for any futures or options contract you can overlay OI as a line that runs the full life of the contract from listing to the chart’s current point. Before that addition, most platforms showed only the current OI number and not its history, which made the change in OI hard to study. The chart study closes that gap and lets you read OI build-up and unwinding visually against price. For interpreting those intraday shifts strike by strike, continue to change in open interest .
A standing caveat from Varsity’s reader discussions: the clean price-OI logic was developed for futures, and reading it directly off option premiums is unreliable, because a change in option OI reflects more open contracts at a strike without mechanically dictating which way the premium moves. Use OI as one input among price and volume, not a standalone signal.
Frequently asked questions
What is open interest in simple terms?
How is open interest different from volume?
Does rising open interest mean the price will go up?
Where can I see open interest on Zerodha Kite?
Is open interest measured in shares or contracts?
Can open interest be higher than the number of shares outstanding?
See also
- Change in open interest
- Put-call ratio
- Max pain theory
- Implied volatility
- India VIX
- Futures and options
- How to use the options chain on Kite
- How to read option Greeks on Kite
- Option premium
- Delta of options
- Gamma of options
- Theta and time decay
- Vega of options
- ITM, ATM and OTM moneyness
- Strike selection for options
- Stock futures lot size on NSE
- Nifty 50
- Bank Nifty
- National Stock Exchange
- Multi Commodity Exchange
- F&O ban period restrictions
- Why scrips enter the F&O ban
- Expiry-day options trading
- Zerodha F&O segment
- Kite by Zerodha
- Zerodha Varsity
- Sensibull
External references
- Zerodha Varsity: What is Open Interest (OI)?
- Zerodha Z-Connect: Open Interest on Kite charts
- NSE: Equity derivatives, market-wide position limits
- NSE: Derivatives daily reports and open interest
- SEBI: Measures to strengthen index derivatives framework, October 2024
References
- Zerodha Varsity, “What is Open Interest (OI)? OI vs Volume in Futures Trading”, Futures Trading module (accessed June 2026).
- Zerodha Z-Connect, “Open Interest on Kite charts, track events, more” (open interest added as a chart study in 2020).
- National Stock Exchange of India, equity derivatives open interest and market-wide position limit reports.
- SEBI circular, Measures to strengthen the equity index derivatives framework, dated 1 October 2024 (contract notional value raised to the Rs 15 lakh to Rs 20 lakh band).