What does OI mean in stock markets?

OI stands for Open Interest. In stock markets, OI means the total number of outstanding futures or options contracts that have not been closed or settled. Each time a new buyer and new seller open opposing positions, OI increases. When either party closes their position against an existing counterparty, OI decreases. OI measures the scale of active participation in a derivative contract.

How is open interest different from volume?

Volume measures the total number of contracts traded during a session — including both opening and closing transactions. Open interest counts only the contracts that remain active (open) at the end of the day. Volume resets to zero every session. OI carries over from one day to the next unless positions are closed. A contract can contribute to volume multiple times in a day but only appears in OI once until it is closed.

What does rising open interest indicate?

Rising open interest indicates that new positions are being added to the market. When OI rises alongside rising prices, it suggests new long positions are being established — a sign of bullish conviction. When OI rises alongside falling prices, it suggests new short positions are being added — a bearish signal. Context from price action is essential for interpreting what rising OI means in any given situation.

Where can I find OI data for Nifty and Bank Nifty?

NSE publishes real-time OI data for Nifty 50 and Bank Nifty through the official option chain available on its website. OI is displayed for each strike price and each expiry series. Many trading platforms including Sahi provide built-in OI displays integrated with option chain data. Historical OI data can be downloaded from NSE's official data portal for analysis.

What is the put-call ratio and how does it use OI?

The put-call ratio (PCR) is calculated by dividing total put open interest by total call open interest for a given index or contract. A PCR above 1 indicates more put positions outstanding than call positions. A PCR below 1 indicates more calls. PCR is used as a sentiment indicator — high PCR can reflect bearish positioning or institutional hedging, while low PCR may suggest bullish sentiment or reduced hedging activity.

Open Interest (OI) Meaning: What OI Data Tells Indian Traders

Open Interest (OI): Meaning, Data, and How It Works in Indian F&O Markets

Learn what Open Interest means, how to analyze OI data, and use it for trading Nifty & Bank Nifty F&O with real examples

Sahi Team

Published: 9 Feb 2026, 12:00 AM IST (2 weeks ago)

Last Updated: 24 Feb 2026, 05:30 AM IST (3 days ago)

4 min read

Open interest (OI) is the total number of outstanding derivative contracts — futures or options — that have not been settled in a market. OI is one of the most widely tracked data points in India's F&O (futures and options) segment.

What Does OI Mean?

OI means the count of contracts that are open — neither closed by an opposing trade nor expired. Each contract in the F&O market involves a buyer and a seller. When both parties open a new position, OI increases by one contract. When a position is closed, OI decreases by one.

OI is not the same as trading volume. Volume counts every transaction during a session — including opening and closing trades. OI only counts contracts that remain open at the end of the day.

OI Data: Where to Find It

NSE publishes OI data for every strike price and every expiry series in the option chain. This data is updated in real time during market hours. Traders can access OI data through NSE's official option chain page, trading platforms with built-in F&O data, and exchange-provided bulk download files for historical OI analysis.

How Open Interest Changes

OI changes based on whether participants are opening or closing positions:

OI increases: When a new buyer enters a new position and a new seller takes the other side — both are opening positions
OI decreases: When an existing buyer closes by selling and an existing seller closes by buying — both are exiting
OI stays flat: When an existing holder closes their position and a new participant opens an opposing position — one opens, one closes

OI in Options: Calls vs Puts

In options markets, OI is tracked separately for call options and put options at each strike price and expiry. High call OI at a specific strike suggests many participants have written or bought calls at that level. High put OI suggests significant put positioning.

Analysts track where OI is concentrated to identify potential support and resistance zones. Heavy call OI at a strike above the current price often indicates resistance — option writers tend to defend these levels. Heavy put OI below the price can indicate support.

Put-Call Ratio (PCR) and OI

The put-call ratio (PCR) based on OI is calculated by dividing total put OI by total call OI for a given index or stock. A PCR above 1 means more puts are outstanding than calls, which can indicate defensive or bearish positioning. A PCR below 1 suggests more call positioning relative to puts.

PCR is used as a market sentiment indicator. However, like all OI-based metrics, it shows positioning rather than direction — high put OI can reflect both outright bearish bets and protective hedges by long holders.

OI and Price Relationship

Price Movement	OI Change	Interpretation
Rising	Rising	Fresh long positions — bullish conviction
Rising	Falling	Short covering — shorts exiting, not new longs
Falling	Rising	Fresh short positions — bearish conviction
Falling	Falling	Long unwinding — longs exiting positions

Limitations of Open Interest Data

OI shows what positions exist — but not the intent behind them. A large put OI could represent outright bearish bets or simple portfolio hedges by institutions holding long stock positions. OI does not reveal whether positions are speculative, directional, or hedging in nature.

OI also does not predict price movement by itself. It is most useful when analyzed in combination with price action, volume, and the broader F&O structure across multiple strikes and expiries.