Total open interest (OI) tells you how many contracts are open at a strike: every position built over days or weeks. Change in open interest tells you how many were added or removed today. It is the column most intraday option traders look at first, because it shows what traders are doing now rather than what they did last week.
Change in OI = open interest now − open interest at yesterday's close
Many option chains show it next to the OI column for both calls and puts, sometimes as a number and sometimes as a percentage. On ScreenerCharts the open interest page charts today's change in call and put OI at every strike and lists the biggest changes, each tagged with what it usually means (for example "Support building" or "Resistance easing"). If OI is new to you, start with what is open interest.
Positive and negative change
- Positive change in OI: more contracts were opened than closed today at that strike. New money is coming in.
- Negative change in OI: more were closed than opened. Traders are leaving.
- Close to zero: either nothing happened, or positions changed hands without new ones being created. Check the volume to tell which.
Change in OI does not say who opened the new contracts (every contract has a buyer and a seller). For that, look at what the option's price did.
Reading change in OI with price
| Change in OI | Option price | Most likely | For a call | For a put |
|---|---|---|---|---|
| Up | Down | Writing | Resistance building | Support building |
| Up | Up | Buying | Traders paying for upside | Traders paying for downside or protection |
| Down | Up | Short covering | Resistance weakening | Support weakening |
| Down | Down | Long unwinding | Call buyers giving up | Put buyers giving up |
It is the same logic as the futures build-up table, applied strike by strike. Keep in mind that option prices fall with time and with falling volatility, so "price down" on a quiet afternoon does not always mean sellers were the eager side.
A worked example on NIFTY
NIFTY closed yesterday at 25,180 and is trading at 25,290 at 13:00 today. Part of the nearest-expiry chain, with OI and change in OI in lakh contracts:
| Call OI | Call change | Strike | Put change | Put OI |
|---|---|---|---|---|
| 32 | −6 | 25,100 | +28 | 96 |
| 48 | −11 | 25,200 | +35 | 88 |
| 71 | +4 | 25,300 | +19 | 52 |
| 92 | +21 | 25,400 | +3 | 24 |
| 118 | +9 | 25,500 | +1 | 12 |
What does it say?
- Put writers added heavily at 25,100 and 25,200 (+28 and +35 lakh) as NIFTY rose. Support has moved up with the market; 25,200 is now the most active put strike today.
- Call OI fell at 25,100 and 25,200 (−6 and −11 lakh). Call sellers there were caught by the rise and covered.
- Fresh call writing went to 25,400 (+21 lakh). That is where today's sellers placed the new cap, even though 25,500 still holds the most call OI in total.
Total OI alone would have pointed to 25,500 as resistance and 25,100 as support. Change in OI shows the newer picture: 25,200 to 25,400 is where today's money is.
Add up the columns and the day's lean is clear too. Calls changed by −6 − 11 + 4 + 21 + 9 = +17 lakh; puts by +28 + 35 + 19 + 3 + 1 = +86 lakh. Put writers added five times as much as call writers. On a day like this the total put-call ratio climbs, and the summary line on the OI page would read that put writers added while the market rose. If the same table had shown call additions of +80 lakh and put additions near zero on a falling day, the story would be the opposite: sellers building a ceiling and nobody defending the floor.
A live example: today's chain
Here is NIFTY's chain around the money right now, with call and put open interest at each strike:
These are totals. To see today's additions at the same strikes, open the change-in-OI chart on the open interest page: the strikes with the biggest additions today are where traders are most active, and they may differ from the strikes with the largest totals shown here. The page also adds up all of today's call and put changes into one line, such as "Put writers added and call writers left: the market leaned up". The day's totals, PCR and max pain are summarised below:
When the PCR is rising through the day, put additions are outpacing call additions, the same story the change-in-OI column tells strike by strike.
Numbers vs percentages
A change of +10 lakh contracts means very different things at different strikes. At a strike with 1.5 crore open, it is under 7%. At a far strike with 12 lakh open, it nearly doubles the position. Both views help:
- Absolute change shows where the most money went. It is better for finding today's main levels.
- Percentage change shows where activity is unusual for that strike. It is better for spotting a strike that suddenly came alive, which can be an early sign of a new level.
For stocks, percentage change in futures OI is the standard measure used to sort the build-up lists, since stocks have very different sizes.
How traders use change in OI
- Finding today's levels: the strikes with the largest call and put additions often act as the day's resistance and support, sometimes more than the strikes with the largest totals.
- Seeing who is under pressure: negative change at strikes the price has just crossed shows which sellers are being forced out.
- Change-in-OI PCR: total put additions divided by total call additions shows which side today's writers favour. See the put-call ratio guide.
- Tracking during the day: the strike OI tracker shows the same change minute by minute, so you can see when it happened, not just how much.
Limits and common mistakes
- The first minutes. Early figures can swing as overnight orders come in. Change in OI means more as the session goes on.
- New series. On the first day of a new weekly expiry, every strike shows a large positive change because the series started from zero. That is not a signal.
- Expiry day. OI falls as positions are closed before settlement, so negative changes everywhere are mechanical.
- Reporting lag. OI updates in steps, a few minutes behind the price.
- Treating it as direction. Change in OI shows where traders committed today. It does not show they are right, and the next session can undo it.
Total OI shows the weight of old positions; change in OI shows today's decisions. Reading both together gives a fuller picture than either alone.