What is Open Interest (OI)?
The Concert Ticket Analogy
Imagine a massive concert that hasn't happened yet. An Option Contract is like a ticket to that concert.
Volume is how many times a single ticket is bought and sold outside the venue by scalpers in a single day. One scalper trading the same ticket 500 times generates massive Volume, but doesn't change the size of the crowd.
Open Interest (OI) is the total number of physical tickets that actually exist in the world right now. It represents the total amount of money and participants definitively locked in and holding positions.
In the derivatives market, Option Writers (Sellers) risk millions of dollars compared to Buyers. Because of this massive risk, Writers are universally considered the "Smart Money." When we analyze these OI columns, we are doing one thing: tracking the Smart Money.
Absolute OI (The Heatmap)
This column shows the total contracts currently locked in at a specific strike price. It represents the structural Support and Resistance walls of the market.
Call (CE) Heatmap
Anchors Right. Red Tone = Resistance
Put (PE) Heatmap
Anchors Left. Green Tone = Support
OI Change (The Flow)
This column tells you the net difference in Open Interest during the current trading session. It answers the question: Is the wall getting stronger right now, or is it collapsing in real-time?
Positive Flow
New Contracts Added
Negative Flow
Contracts Unwound
OI Change % (The Momentum Standardizer)
Raw integers can be misleading. An addition of +50,000 contracts is meaningless if the base OI is already 10 million. But if the base OI was only 10,000, that +50,000 is a massive anomaly.
Explosive Growth
Massive % surge highlights institutional conviction
Volume (The Engine)
Volume represents total trades executed. In the Sahi chain, Volume cells are rendered with heatmaps identically to the Absolute OI cells, but relative to the maximum Volume on the board.
High Volume Node
Indicates intense intraday trading activity
Volume / OI Ratio (The Speculation Index)
Derived by dividing the current day's Volume by the Absolute OI. Sahi strips away heatmaps and colors for this cell, letting the raw number tell the story.
Speculation Index
Volume is 2.85x greater than the existing Open Interest
Build-Up Signals (The Synthesis Matrix)
The final column algorithmically synthesizes Premium Price direction with OI direction, translating it into an explicit Market Sentiment badge.
Buyers are paying higher premiums. Upward momentum.
Writers are actively shorting, creating massive walls.
Writers are trapped and buying back to exit.
Buyers are giving up and closing positions.
Test Your Knowledge
Check the mechanics before you take them to a live chain.
1. If Price is Rising and OI is Falling, what is happening?
2. A Volume/OI Ratio of 3.5 indicates what?
About the Sahi Option Chain
The Sahi option chain shows every strike of the selected NSE or BSE underlying in a single live grid — call and put open interest, change in open interest, volume, bid and ask, last traded premium, implied volatility and the full set of Greeks.
Data streams directly from the exchange feed during market hours, so open interest and premium move as the market moves rather than on a delayed refresh. Each row also carries a build-up classification, so long build-up, short build-up, short covering and long unwinding are readable without doing the arithmetic yourself.
At a glance
- Data
- Live NSE and BSE exchange feed
- Updates
- Continuously, through market hours
- Coverage
- NIFTY, BANKNIFTY and NSE F&O stocks
- Access
- Free — no login, no download
- Orders
- Analysis only. Sahi does not accept orders
See it on today's numbers
Everything above is method. These articles apply it to a live book — open interest among the rest — and are rebuilt as the snapshot data refreshes. Where a symbol's option book is too thin to support a reading, the article says so rather than asserting a level.
Frequently asked questions
What is open interest in options?
Open interest is the total number of option contracts in a strike that are still open and not yet squared off or settled. It counts positions, not trades. Rising open interest means fresh contracts are being created and new money is entering that strike; falling open interest means existing positions are being closed out.
How do I read the option chain to find support and resistance?
Look for the strikes carrying the largest put and call open interest around the current spot. The heaviest put strike below spot is commonly treated as a support reference and the heaviest call strike above spot as resistance. Then watch change in open interest through the session — a level being defended will keep adding open interest, while a level about to break usually sheds it.
What does change in open interest tell me that open interest alone does not?
Change in open interest shows what is happening today, while standing open interest shows what was already there. A strike can hold a very large position built up over weeks yet see no fresh activity, and another can be quiet in absolute terms but adding aggressively right now. Reading both together separates old positioning from live intent.
What is the difference between open interest and volume?
Volume counts every contract traded during the session and resets to zero the next day, while open interest counts contracts still outstanding and carries forward until they are closed or expire. High volume with rising open interest points to fresh positioning; high volume with falling open interest points to existing positions being unwound.
Why do call and put implied volatility differ at the same strike?
Implied volatility is set by supply and demand for each contract separately, so the same strike can price its call and its put differently. Persistent gaps usually reflect directional demand — heavier put buying lifts put implied volatility, producing the downside skew commonly seen in index options. Watching the gap widen or narrow is itself a read on positioning.
Explore more Sahi tools
Every tool runs on the same live feed and keeps whichever instrument you have selected, so you can move between them without re-picking the symbol.
Option Chain
Open Interest
Every Sahi guide
Each guide pairs with a live tool. The options FAQ collects every question from all of them in one place.