Change in OI in Option Chain: What It Really Means

Change in OI is the number next to Open Interest in the option chain — how many contracts got added or closed off at a strike since the previous close. A rising number means new positions opened; a falling one means positions closed out. But the number alone won't tell you if the market is turning bullish or bearish. For that, you need to check what price did at the same time.

Why Rising or Falling OI Alone Doesn't Tell You the Direction

Say someone in your trading group forwards a screenshot: "OI at Nifty 25000 CE just jumped from 30,000 to 48,000 contracts in an hour — massive bullish buildup!" That claim is only half-checked.

OI rising tells you fresh money entered that strike. It says nothing about whether those fresh contracts are people buying calls because they expect Nifty to rise, or people writing calls because they expect it to stay capped below 25,000.

Both actions raise OI. Only one of them is actually bullish. The only way to tell them apart is what the option's premium did at the same time. Did it rise, with buyers paying up and pushing price higher? Or fall, with writers selling more and dragging price down?

Reading Change in OI With Price: The Four Patterns

Pair the direction of price with the direction of change in OI at that strike, and you get one of four standard patterns traders use to read an option chain.

Each of these has its own quick-reference page if you want the one-line version: Long Buildup, Short Buildup, Short Covering, and Long Unwinding.

A Worked Example From a Live Option Chain

Here's how this looks with real numbers on a Nifty strike.

1. Vikram checks yesterday's close. He's a Pune-based equity investor who moved into index options this year. At yesterday's close, Nifty 24800 CE (a call option) had Open Interest of 42,000 contracts and a premium of ₹145.
2. He checks the same strike price mid-session today. The premium has dropped to ₹95, and OI on that strike price has climbed to 58,000 contracts.
3. He reads price and OI together, not separately. Premium down, OI up — that's Short Buildup. Traders are writing fresh 24800 CE contracts, betting Nifty won't close above 24,800 by expiry.
4. He treats it as a signal, not a certainty. Change in OI here is 58,000 − 42,000 = 16,000 contracts. That's a meaningful jump in one session, and it tells Vikram fresh sellers are building a position around 24,800 — useful context for where resistance might build, not proof that Nifty will stop there.

Nifty's lot size is 75 contracts at the time of writing. Confirm the live figure before trading, since NSE revises lot sizes periodically.

Change in OI vs Volume: What's the Difference

Change in OI and volume are not the same number, even though most option chain views show them side by side. Volume counts every contract traded that session, whether the position stayed open or not. Change in OI counts only the net contracts still open at the end of it.

If a trader buys 10 lots of Nifty 24800 CE in the morning and sells all 10 back before the close, that adds 10 lots to volume but zero to Change in OI — the position never stayed open. A strike can show heavy volume and almost no OI change on a day when a lot of intraday trading happened but few positions carried forward.

If you're trying to judge whether a strike's move is likely to matter beyond the day, Change in OI is the number to check, not volume. High volume with flat OI usually means day traders churning the strike, not a position building up.

Put OI vs Call OI: What It Tells You About Sentiment

Comparing how Put OI and Call OI change on the same expiry tells you which side is adding positions faster: buyers of downside protection, or buyers of upside bets. A sharp rise in Put OI relative to Call OI usually points to more hedging or bearish positioning building up. The reverse points the other way.

This comparison, extended across every strike in the chain, is exactly what the Put Call Ratio (PCR) measures. Read that piece for how to calculate it and what counts as a high or low PCR for Nifty and Bank Nifty.

Where to Check Change in OI in a Live Option Chain

NSE's own option chain tool shows this live, and so does every major broker's app.

1. 1

   Open NSE's option chain page (or your broker's option chain view) for the index or stock you're tracking.

2. 2

   Select the underlying and the expiry you want to check.

3. 3

   Find the "Chng in OI" column next to the OI column, calls on the left and puts on the right.

4. 4

   Sort by that column to see which strikes moved the most that session.

Refresh through the session. Change in OI resets against the previous day's close, so the number keeps growing, or reversing, as the day goes on, not just at close.

Common Misunderstandings