The option chain is a live table of every call and put strike for an expiry, showing you how many contracts are open at each strike and how that number is changing through the day.
Most traders look at the option chain and see a wall of numbers that feels important but hard to interpret. It is genuinely useful data, but only once you understand what each column is actually counting. This post explains open interest, change in open interest, put call ratio, and max pain in plain terms, and where each one is reliable and where it is not.
What open interest actually counts
Open interest, OI, is the total number of option contracts at a given strike that are currently open, meaning bought or sold and not yet closed out or expired. It is not the number of contracts traded today. That is volume, a separate column. OI is the running total of live positions.
High OI at a strike means a large number of contracts are currently held open there. It does not by itself tell you whether those positions are bullish or bearish, because both a buyer and a seller are on each contract. What it tells you is that a meaningful amount of capital and attention is concentrated at that strike, which is exactly why high-OI strikes often behave like support and resistance for the underlying.
Why high OI strikes act like support and resistance
When a strike carries very high call OI, a large number of traders have sold or bought calls there. Option sellers at that strike, who are often larger, better capitalised participants, have an incentive to defend that level, since a breach that makes their short calls go deep in the money is expensive for them. This creates real buying or selling pressure around heavily populated strikes as expiry approaches, which is why traders watch these levels alongside plain price chart support and resistance rather than instead of it.
This effect is strongest closer to expiry and weaker earlier in the series, since positions can still shift substantially in the days ahead.
Change in open interest tells you more than the raw number
The raw OI number is a snapshot. Change in OI, how much that number has grown or shrunk since the previous session or since the morning, tells you where fresh positions are actively being built right now.
Reading price direction alongside change in OI gives you a more complete picture than either alone.
- Price up, OI up: new long positions being built, generally read as a genuine bullish move backed by fresh buying.
- Price up, OI down: existing short positions being covered rather than new buying, a move that can run out of steam once the covering is done.
- Price down, OI up: fresh short positions being built, read as genuine bearish pressure.
- Price down, OI down: long positions being closed out, not necessarily fresh bearish conviction.
This framework, applied to the underlying futures or to specific option strikes, is one of the more genuinely useful reads the option chain offers, because it separates a move driven by fresh conviction from a move driven by unwinding of old positions.
Put call ratio, and why it is a sentiment gauge, not a signal
Put call ratio, PCR, compares total put OI to total call OI across the chain. A PCR above 1 means more put OI than call OI outstanding. A PCR below 1 means the reverse.
PCR is commonly read as a contrarian sentiment gauge. A very high PCR suggests heavy put buying or writing, often associated with excessive bearishness, which can sometimes precede a bounce, since sentiment extremes tend to reverse. A very low PCR suggests excessive bullishness, which can sometimes precede a pullback.
Treat this as a background sentiment read, not a trade trigger on its own. PCR can sit at an “extreme” reading for extended stretches during a genuine strong trend, exactly like RSI staying overbought through a strong uptrend. Trading PCR in isolation, without price confirmation, has the same failure mode as trading any single oscillator in isolation.
Max pain, and why it deserves modest weight
Max pain is the strike price at which the maximum number of option buyers, across both calls and puts, would lose the most money at expiry, calculated from the current open interest distribution across the chain.
The theory behind max pain is that large option writers have some incentive to see the underlying settle near this level, since it minimises the payout to option buyers. In practice, this effect is real but modest, and it competes with far larger forces like broader market direction, news, and overall liquidity. Max pain is worth checking as one input, particularly in the last day or two before expiry, but treating it as a reliable prediction of where price will land is not supported by how large and liquid Nifty and Bank Nifty actually are.
A worked example on Nifty options
Say Nifty is at 24,700 with two days left to weekly expiry. The 24,800 call strike is carrying the highest call OI on the chain, well above neighbouring strikes. The 24,600 put strike is carrying the highest put OI. On the price chart, 24,800 also happens to line up with a swing high from ten days ago, and 24,600 lines up with a level where price bounced twice last week.
Through the morning, Nifty drifts up toward 24,780. You check change in OI on the 24,800 call and see it has been rising through the session, not falling. Under the framework covered above, price moving up while OI at that strike also rises, on the call side, tells you fresh call writing is happening there, sellers are actively defending 24,800 rather than existing shorts simply getting caught and covering. That is a meaningfully different situation from a case where the call OI at 24,800 was falling while price approached it, which would suggest sellers backing away rather than defending the level.
Now say Nifty pushes through 24,800 anyway, closing the session at 24,850 with the call OI at 24,800 dropping sharply during the move. That drop tells you the sellers who were defending the strike got forced to cover, buying back their calls as price broke through, which itself can add fuel to the move. Reading the OI change alongside the price break gives you a fuller picture than the price break alone would, since it tells you whether the level failed quietly or failed because defenders were forced out.
Why max pain has limited pull on a large index
It helps to understand why max pain works better in theory than in practice for an instrument like Nifty. The max pain calculation only accounts for the current distribution of option positions on the chain. It says nothing about the far larger flows moving the underlying itself, such as institutional buying or selling in the cash and futures market, global cues, or news. For a small, thinly traded stock with limited float and a chain dominated by a handful of large writers, those writers pushing price toward max pain is a more plausible mechanism, because their positions are a meaningful share of total activity. Nifty is a broad index with enormous daily turnover across cash, futures, and options combined, and no single set of option writers controls enough of that flow to reliably steer the index toward one strike. This is the actual reason max pain deserves only modest weight on Nifty and Bank Nifty specifically, not a general dismissal of the idea, since the same logic can carry more weight on a much smaller, less liquid stock.
Reading the chain alongside the price chart, not instead of it
The option chain is a sentiment and positioning tool. It works best layered on top of the price chart reading covered elsewhere on this site, not as a replacement for it. A high-OI strike that also lines up with an existing swing high or low on the daily chart is a stronger level than either signal alone. A PCR extreme that also coincides with price sitting at a major support level carries more weight than PCR viewed in isolation.
The execution angle
Option chain data updates constantly through the day, and it is easy to get pulled into refreshing it every few minutes, watching OI shift strike by strike, and mistaking that activity for productive analysis. In practice this often produces more hesitation, not more clarity, because minor OI shifts through the day are largely noise around the more meaningful levels set earlier. Knowing which OI reads matter and having the discipline to check the chain at set points rather than continuously are two different skills, and the second one protects you from turning genuine data into a source of constant, low-value distraction.
Frequently asked questions
What is a good PCR value to watch for?
There is no single fixed number that works across all conditions. Extremes are relative to the recent range for that instrument. Watch how current PCR compares to its own recent history rather than anchoring to one hard number.
Is high open interest always bullish or bearish?
Neither by itself. High OI shows concentration of positions at a strike, not direction. Combine it with change in OI and price movement to read whether the positioning behind it is fresh conviction or unwinding.
Does max pain reliably predict the expiry close?
Not reliably enough to trade on its own. It is a modest gravitational pull among several larger forces. Treat it as one input near expiry, not a forecast.
How often should I check the option chain during the day?
Checking at defined points, such as the morning, midday, and near the close, is usually more useful than continuous refreshing, which tends to surface noise rather than meaningful shifts.
Is the option chain more useful for Nifty or for individual stocks?
Nifty and Bank Nifty option chains are generally more reliable due to far higher liquidity and tighter spreads. Option chains on lower-liquidity stocks can show wider, less meaningful OI swings that are harder to interpret confidently.
The real point
The option chain is genuinely useful data about where positions are concentrated and how sentiment is shifting. It is not a crystal ball, and treating any single column, OI, PCR, or max pain, as a standalone signal repeats the same mistake traders make with any single indicator viewed in isolation.
Read it as one layer of context alongside the price chart, and resist the pull to keep refreshing it in search of certainty it was never built to give you.
Data poori mil sakti hai, certainty kabhi nahi.
Related reading:
- How to Choose the Right Trading Timeframe for You
- Moving Averages: How Traders Actually Use Them
- The First 60 Seconds After You Enter a Trade
Knowing how to read OI and PCR correctly does not stop the urge to keep refreshing the chain looking for certainty it cannot give you. I run a free live session twice a week for traders with two or more years of experience who know the setups but still cannot execute under pressure. Register for the next free session here.
I am Samir Dash, founder of Mindful Trading Hub. I work with experienced traders on live market decision-making. More about my story here.
