How to read an option chain in India

The chain is built around the strike ladder in the centre, running from low strikes at the top to high strikes at the bottom. To its left is everything about the call at each strike; to its right, everything about the put. The two sides are a mirror, so a single horizontal row lets you compare the call and the put that share a strike, and a single vertical column lets you see how one quantity, say open interest, changes as you walk up or down the strikes.

The anchor is the at-the-money (ATM) strike, the one closest to the current spot level of the underlying. Above the ATM, calls are out-of-the-money and puts are in-the-money; below it, the reverse. Most chains shade the in-the-money side, so the boundary between light and dark cells is the spot, and you can find the ATM at a glance without reading a single number.

One more control sits above the grid: the expiry selector. A chain shows one expiry at a time, and the same strike carries a different premium, a different implied volatility and a different open interest for the near expiry than for the next one. Liquidity is deepest in the nearest expiry, so most reading starts there, but comparing the near and next expiry for one strike is how you watch the market's view lengthen: the further expiry almost always carries the richer premium, because it buys more time for a move to happen. Always check which expiry you are reading before a single number, because a premium that looks cheap may simply belong to a nearer expiry with less time left in it.

Five quantities do the work on each side of the chain, and each answers a different question. Confusing them is the root of most misreadings, so it is worth stating precisely what each one is and, just as important, what it is not.

The premium (LTP) is the last traded price of that specific option, quoted per unit; your actual outlay is that figure times the lot size. Bid and ask are the best resting buy and sell prices, and the gap between them, the spread, is the immediate cost of transacting: a wide spread means you lose ground the instant you enter. Volume is the count of contracts traded so far today, a measure of activity that resets at the next open. Implied volatility (IV) is the volatility the market is pricing into that option, backed out of its premium; higher IV means a richer premium for the same strike and expiry. And open interest (OI) is the number of contracts currently outstanding at that strike, with change in OI showing how that stock moved during the session.

To make the columns concrete, read the at-the-money row of the table above from the outside in. At the 25,000 strike the call last traded at 168 and the put at 152, so a single lot of either, at an illustrative lot size, would cost that premium times the lot. Both sides show an implied volatility near 13.7, the lowest on the visible ladder, because the at-the-money strike sits at the floor of the smile. The heaviest open interest is not here but out at the 25,200 call and the 24,900 put, the crowded strikes. And the change-in-OI column is positive across the row, which says fresh positions were added today rather than closed. That is the whole chain in one habit: read a row for the trade in front of you, read a column to see where the crowd has gathered.

The subtle line in that table is between volume and open interest, because they are the two most cited numbers and the two most often conflated. They are not the same kind of thing at all: one is a flow, the other a level.

Think of the strike as a reservoir. Volume is the water that flowed through the pipe today, and it is reset to zero every morning. Open interest is the level actually standing in the reservoir, and it carries from one day to the next. Open interest rises only when a genuinely new contract is created, a fresh buyer meeting a fresh seller, and falls only when an existing position is closed. If two traders simply pass an existing contract between them, volume ticks up but open interest does not move at all. That is why volume can far exceed open interest on a busy day, and why change in OI is often the more informative figure: it isolates the fresh positioning from the churn.

Here is where a chain guide has to choose between being useful and being popular. The popular reading is simple: a strike with heavy put open interest below the spot is called support, a strike with heavy call open interest above it is called resistance, and the put-call ratio is quoted as a sentiment gauge. If open interest itself is still fuzzy, the dedicated guide to open interest in trading covers the plumbing; the concern here is narrower, how to read it without over-reading it. The popular logic is not nonsense: large written positions do cluster at round strikes, and the writers of those options have an interest in the price staying away from them, which can create real friction at those levels.

But that reading omits the single most important fact about open interest, and it is the differentiator of this guide: open interest cannot tell you the direction of a position. Every open contract has a buyer and a seller, so the number counts pairs, not a net stance. A jump in open interest at a call strike is equally consistent with a bull buying the call, a bear writing it, a fund hedging its stock, or a trader legging into a spread. The figure is identical in all four cases. Open interest is a measure of how much is committed at a strike; it is silent on who is committed, on which side, and why.

So the single most honest thing to say about open interest is that it is descriptive, not predictive. It is a photograph of where commitment sits, taken from an angle that hides which way anyone is facing. That does not make it useless, but it makes it a starting point rather than a verdict, and it means the popular habit of reading crowded strikes as hard levels asks the number to do something it structurally cannot. What open interest can support, and what it cannot, divides cleanly enough to lay out side by side.

The one genuinely analytical use of open interest is to read its change alongside the change in price over the same window. This pairing is where traders infer whether a move is backed by fresh commitment or is merely old positions unwinding. There are four combinations, and each carries a conventional label. The important word throughout is infer: these are reasonable readings of positioning, not certainties, because, as above, the same OI change can come from a hedge or a spread rather than a directional view.

Used carefully, the matrix answers a narrow question well: is this move being driven by people arriving or people leaving? That distinction matters, because a rally on short covering is a different animal from a rally on fresh buying, and it can fade the moment the trapped shorts are done. But the matrix is still an inference layered on a number that hides direction, and it is at its weakest exactly when it feels most confident, in the middle of a violent move, when hedging flow and forced exits muddy every reading.

Every column so far has described a price or a position. The chain also does something quietly powerful: it hands you the market's own estimate of how far the underlying is likely to move by expiry, and it does so through the at-the-money straddle. A straddle is simply the call and the put at the same strike, taken together. At the at-the-money strike, the sum of the two premiums is the number to watch, because it is precisely what the market is charging for a bet that pays off in either direction.

The arithmetic is deliberately blunt. Take the strike nearest the spot, add the call premium to the put premium, and you have the straddle price in points. On an illustrative chain with the spot at 25,000, an at-the-money call at 168 and an at-the-money put at 152, the straddle is 320 points. That 320 is the market's priced move: to profit from buying both legs, the index must travel more than 320 points one way or the other by expiry. Read the other way, the market is pricing a move of roughly plus or minus 320 points, a band from about 24,680 to 25,320, and charging you exactly that to take the other side of it. It is an estimate of the size of the move, never its direction.

This is the same idea the India VIX expresses for the whole index. India VIX reads the near-term index option book and republishes it as one annualised percentage covering a rolling thirty days; the at-the-money straddle is that same expected-move information for one specific expiry, already denominated in the points you would measure a stop or a target against. If the annualised-percentage version is unfamiliar, the guide to the India VIX works through the conversion from a percentage to a rupee move. Two honest caveats belong here. The straddle approximates a one standard deviation move, not a promise; realised moves come in smaller than it most weeks and violently larger in the few that matter. And it widens mechanically with time to expiry, which is why the same strike shows a larger straddle for a later date.

The table makes the time effect concrete. The weekly straddle prices the smallest move because there is the least time for one to happen; the monthly prices the largest. None of these is a forecast that the index will move that far. Each is the cost of a bet that it will, set by the balance of everyone willing to buy and sell that bet right now. Read it as the market quoting its own uncertainty, in points you can act on, and you are reading it correctly. This is also the most direct answer to why a far out-of-the-money weekly option can look so cheap: the straddle shows you how little room the market expects, and a strike well outside the band is being priced as unlikely for a reason.

Return to implied volatility, defined earlier as the volatility the market is pricing into an option. The tempting mistake is to treat it as a single reading for the underlying, as though the chain carried one IV. It does not. Implied volatility is quoted per option, and it differs from strike to strike. Plot it against the strike ladder and it traces a curve, not a flat line, and the shape of that curve is itself information about what people are paying up for.

In equity index options the curve is usually not a symmetric smile but a skew, sometimes called a smirk: out-of-the-money puts carry visibly higher implied volatility than out-of-the-money calls. The reason is demand. A fall in the index tends to be faster and more feared than a rise of the same size, so traders and institutions bid up downside puts as crash insurance, and that demand shows up as richer implied volatility on the low strikes. The at-the-money strike tends to sit near the low point of the curve, with both wings lifting away from it, the downside wing more steeply. If the mechanics are still hazy, the guide to implied volatility covers how it is backed out of a premium in the first place.

Read the smile the way you read the straddle, as a map of what risk costs at each strike. It tells you where protection is dear and where leverage is cheap, and a sudden steepening of the downside wing is a real signal that demand for insurance has jumped. What it never tells you is which way the underlying will break. Any reading that claims the skew predicts the next move has quietly crossed from description into prophecy, which is the exact error this whole guide is written to prevent.

One number on the chain is quoted more often than any other and understood less: the put-call ratio, or PCR. It divides total put open interest by total call open interest, or sometimes put volume by call volume, into a single figure. A ratio above one is read as put-heavy and cautious; a ratio below one as call-heavy and bullish. It is genuinely a summary of positioning, and as a rough temperature reading it is not worthless.

But it is over-read more than almost anything else on the screen, for three structural reasons. It is a lagging summary of positions already taken, so it describes the past rather than the next move. It cannot separate a hedge from a bet: a fund buying puts to protect a large stock holding lifts the ratio exactly as a bearish speculator would, and the number cannot tell them apart. And it is easily distorted, because a single large institutional trade can swing the whole ratio in a way that says nothing about the wider crowd. Worse, it is often inverted into a contrarian trigger, so an extreme reading gets taken as a reason to fade the crowd, which turns a descriptive statistic into a prediction it was never built to make.

The put-call ratio is a thermometer read as a crystal ball. It can tell you the room is warm. It cannot tell you what happens next.

The honest use is narrow. A PCR is one rough input among many, best read as a change over time on a single underlying rather than as an absolute level. It can confirm a story you already have evidence for; it should not start one. Treated that way it is a modest, occasionally useful gauge. Treated as a standalone trigger, it misleads more often than it helps, which is why it earns a place on this page mainly as the clearest example of the guide's central warning: a descriptive number read as a predictive one.

In India the option chain is a public utility. The NSE publishes it free on its website, updated in near-real time through the trading session, so there is no cost or subscription to see strike-wise open interest, change in OI, volume, implied volatility and the put-call ratio. Index options carry both weekly and monthly expiries, while single-stock options settle monthly. One point of currency matters, because it dates careless guides: as of 17 July 2026 the exchanges have rationalised weekly index expiries, so fewer indices carry a weekly expiry than older articles assume, and the arrangements continue to change. Always confirm the live expiry list on the exchange itself before you read anything else, rather than trusting a roster printed in any guide, including this one.

Liquidity is not spread evenly across the chain. It concentrates near the at-the-money strike and in the nearest expiry, where the bid-ask spread is tightest and the depth is real. As you move to far out-of-the-money strikes or far-dated expiries, volume thins and the spread widens into a genuine cost: the LTP may look like a price, but there is no one there to trade it at that figure. This is also where the arithmetic of options turns against the impatient. A far out-of-the-money weekly option looks cheap because its probability of paying off is low, and its time value drains quickly as expiry nears even when the underlying barely moves. The chain shows you the price. It does not show you the timing risk you take on by paying it.

Read plainly, the option chain is a live inventory of prices, costs and positioning across every strike of an expiry. That is a great deal, and it is genuinely useful: it tells you what an option costs, how expensive its volatility is, how liquid it is to trade, where the expected move sits, and where the crowd has gathered. What it is not, at any column, is a forecast. The premium is a price, not a prediction. Implied volatility is a cost, not a direction. The at-the-money straddle is the market pricing the size of a move, not calling its way. Open interest is a stock of commitments whose direction is hidden by construction. Even the buildup matrix, the most analytical thing on the screen, only tells you whether a move is arrival or exit, and only as an inference.

So the skill the chain rewards is not pattern-spotting on a data-dense screen; it is knowing the exact boundary of what each number can support, and refusing to read past it. That discipline, holding a claim to what the evidence actually shows and no further, is the same judgement that separates a durable trader from a busy one, and it is exactly what the method we teach is built around. The chain hands you the facts. Reading them without inventing a story is the entire game.

• NSE option chain. The National Stock Exchange publishes the option chain free and public, showing strike-wise open interest, change in OI, volume, implied volatility, the put-call ratio and the last traded price for index and stock options, updated in near-real time during market hours. nseindia.com
• Open interest, and its distinction from volume. Standard derivatives references establish the mechanics of open interest as the stock of outstanding contracts that changes only when positions are created or closed, its difference from daily traded volume, and the price-and-OI interpretation grid used to infer long buildup, short buildup, short covering and long unwinding.
• The at-the-money straddle and the expected move. Standard options references treat the sum of the at-the-money call and put premiums as the market's estimate of the move by expiry, an approximation of a one standard deviation range, which is the same information the India VIX expresses for the whole index as one annualised percentage.
• The volatility smile and skew. Implied volatility varies by strike, and equity index options characteristically show a downside skew, with out-of-the-money puts priced at higher implied volatility than out-of-the-money calls, a shape that reflects demand for downside protection rather than any forecast of direction.
• SEBI derivatives-loss study. The Securities and Exchange Board of India study of individual traders in the equity derivatives segment (September 2024) reported that about 93% of individual traders made net losses over FY22 to FY24, with aggregate net losses exceeding ₹1.8 lakh crore, underscoring how much of the loss concentrates in low-probability options. sebi.gov.in