How to Use the Option Chain for Intraday Trading in Indian Markets

What the option chain actually shows you

The option chain on the NSE website is a single table for one expiry of one underlying, for example weekly Nifty. Calls sit on the left, puts on the right, and the strike prices run down the middle. For each strike you see the premium (last traded price), the open interest, the change in open interest since the previous close, the day volume and the implied volatility. The strike nearest the current index level is the at-the-money strike, and intraday traders spend most of their attention within two or three strikes either side of it because that is where premiums move fastest and liquidity is deepest.

Open interest is the number of contracts still open, not closed. It is the crowd's parked money. Volume is how many contracts changed hands today. A strike can have huge OI but low volume, which means traders built positions earlier and are now sitting tight. The single most useful intraday habit is to compare change in OI with the price action. Rising OI with a rising premium means fresh buyers are committing. Rising OI with a falling premium means fresh sellers (writers) are committing. Falling OI means the existing position is being squared off, which is often what causes the sharp expiry-day moves.

Implied volatility (IV) tells you how expensive the option is relative to expected movement. When IV is high, premiums are fat and option buyers are paying up for movement that may not come. When IV is low, premiums are cheap but a quiet market may keep them cheap. For intraday volatility matters because a single India VIX spike around news can inflate premiums even when the index barely moves.

Support, resistance and the max pain level

Option writers are usually well-capitalised institutions, so the strikes where they sell heavily tend to act as walls. The strike with the highest call OI is treated as intraday resistance, because call writers there profit if the index stays below that strike. The strike with the highest put OI is treated as support, because put writers there profit if the index stays above it. These are not magic lines, they are simply where a lot of money wants price to stay, and they often hold until a strong trend forces that OI to unwind.

Max pain is the strike at which the largest number of options expire worthless, meaning option buyers as a group lose the most and writers keep the most premium. Price often drifts toward max pain near expiry, especially on quiet weekly Tuesdays for Nifty. Treat it as a magnet, not a guarantee. A trending day driven by global cues or RBI policy will override max pain easily.

Reading the Put Call Ratio for a quick sentiment check

The Put Call Ratio by OI is total put open interest divided by total call open interest across the chain. A reading near 1.0 is balanced. Below about 0.7 the market is heavily skewed to calls, which can mean either genuine bullishness or an overbought, complacent setup ready to reverse. Above about 1.3 the skew is to puts, which can mean either real fear or an oversold market that may bounce. The PCR is a contrarian-friendly clue, not a buy or sell button. Use it alongside price structure and the OI shift, never alone.

A fully worked Nifty intraday example with real numbers

Here is an illustrative weekly-expiry session. Numbers are realistic for a recent Nifty level but are examples only and not a recommendation or a promise of returns. Suppose Nifty spot opens around 23,450 and you pull up the weekly option chain. You scan the strikes near the money and note the open interest and premiums below. The 23,500 call carries the heaviest call OI on the chain and the 23,300 put carries the heaviest put OI, so your working intraday range is roughly 23,300 support to 23,500 resistance.

By mid-morning you see the 23,300 put adding OI fast while its premium drops from 62 to 48, which is classic fresh put writing, a bullish tell because writers are betting the index holds above 23,300. At the same time the 23,500 call OI starts falling and its premium rises from 58 to 74, meaning call writers are covering. Both signals point the same way, so you take a long view and buy one lot of the 23,450 call at a premium of 95. Nifty's lot size is 65, so your cost is 95 multiplied by 75, which is Rs 7,125 plus charges.

Nifty grinds up to 23,540 by early afternoon. Your 23,450 call is now in the money and its premium has risen to 138. You exit. The gross gain per unit is 138 minus 95, which is 43 points. Multiplied by the 65 lot size that is Rs 2,795 gross on one lot. That is the headline number, but you have not paid the broker, the exchange or the government yet, and on an intraday options trade those costs are not trivial.

The same trade after brokerage, STT and taxes

Now subtract realistic costs on a discount broker like Zerodha, which charges a flat Rs 20 per executed order on options. One buy plus one sell is two orders, so brokerage is Rs 40. Securities Transaction Tax (STT) on options is 0.1 percent of the sell-side premium value. Your sell value is 138 multiplied by 75, which is Rs 10,350, so STT is about Rs 10.35. GST at 18 percent applies on brokerage plus transaction charges. Exchange transaction charges on NSE options are roughly 0.035 percent of premium turnover, SEBI charges and stamp duty add a few rupees more.

• Gross profit: 43 points multiplied by 65 lot equals Rs 2,795.
• Brokerage: Rs 20 buy plus Rs 20 sell equals Rs 40.
• STT on sell side: 0.1 percent of Rs 10,350 equals about Rs 10.35.
• Exchange transaction charges plus SEBI plus stamp duty: roughly Rs 8 to Rs 12 across both legs.
• GST at 18 percent on brokerage plus transaction charges: roughly Rs 9.
• Total costs: approximately Rs 68 to Rs 72.
• Net profit before tax: roughly Rs 3,155 on one lot.

On this winning trade costs ate roughly Rs 70, which is about 2 percent of the gross. That feels small here only because the move was 43 points. On a scalp where you book 8 or 10 points, the same fixed brokerage and STT can swallow a quarter or more of the gross, which is why high-frequency intraday option buying needs a high win rate or a tight cost structure to survive.

How F&O profits are taxed in India

This is where many new option traders get a nasty surprise. Income from futures and options is treated as business income, not capital gains. So the 20 percent short-term capital gains rate and the 12.5 percent long-term rate above Rs 1.25 lakh that apply to delivery equity do NOT apply to your intraday option trades. Instead your net F&O profit for the year is added to your other income and taxed at your normal slab rate, the same way salary or business profit is taxed.

That means if you are in the 30 percent slab, roughly 30 percent of your net annual F&O profit goes to tax, after you deduct legitimate expenses like brokerage, internet, advisory and data subscriptions. You can also set off F&O losses against most other business income and carry forward unabsorbed losses for up to eight years if you file your return on time. Because F&O is business income, a tax audit under Section 44AB may apply once turnover crosses the prescribed limit, so keep clean records and a contract note for every trade.

• F&O profit equals business income, taxed at your slab rate, not at 20 percent STCG or 12.5 percent LTCG.
• STT on sold options is 0.1 percent of premium, charged on the sell leg.
• Brokerage, data and advisory costs are deductible business expenses against F&O profit.
• Losses can be set off and carried forward up to eight years if the return is filed on time.
• A tax audit may be required above the turnover threshold, so maintain contract notes and a trade log.

Expiry mechanics and SEBI rules you must respect

Index options are cash settled, so you never take delivery. Nifty weekly options expire on Tuesday and the monthly contract is the last Tuesday's expiry. Stock options are monthly only. After SEBI's 2024 and 2025 moves to cool retail speculation, each exchange now offers weekly expiry for only one benchmark index, so the number of weekly expiries available has been reduced. Always confirm the current weekly expiry day and the live contract list on the NSE site before you trade, because these specifications change.

On expiry day, time decay accelerates brutally. An out-of-the-money option that is 100 points away with two hours left can go to near zero in minutes if the index does not move. This is why writing (selling) options near max pain on expiry afternoon is popular, and also why buying cheap far OTM options as a lottery ticket usually loses. SEBI has also raised lot values and margin requirements, so the capital and risk per lot are higher than they were a few years ago. Position sizing on expiry must account for both the leverage and the speed.

Common mistakes intraday option traders make

The biggest error is treating the option chain as a crystal ball. OI tells you where money is parked, not where price must go. A second common error is ignoring time decay. Many beginners buy ATM or OTM calls in a sideways market, watch the index go nowhere, and still lose money because the premium bled away. A third is over-leveraging. Because one Nifty lot controls 65 units, a small adverse move multiplies fast, and traders who buy three or four lots on a tight account get wiped out by ordinary intraday noise.

• Reading OI as a guarantee instead of a probability weighted clue.
• Forgetting that bought options lose to theta every hour, especially on expiry day.
• Over-leveraging by stacking lots on a small account.
• Chasing far OTM cheap options that look like a bargain but rarely pay.
• Ignoring India VIX and event risk, so an IV crush after the news wipes the premium.
• Not counting brokerage, STT and GST, which quietly turn a small gross win into a net loss on scalps.

A practical intraday checklist using the chain

Before you click buy, run a short routine. Mark the heaviest call OI strike as resistance and the heaviest put OI strike as support, so you know your room. Check the change in OI to see who is committing fresh money. Glance at the PCR and India VIX for the broad mood. Confirm with price structure on the chart, ideally an intraday technical analysis level or trend, before acting on the chain alone. Then size the position so a full stop loss is money you can lose without stress.

• Identify support and resistance from the heaviest put and call OI strikes.
• Read the change in OI to spot fresh writing or covering, not just the static OI.
• Check PCR and India VIX for the broad sentiment and premium richness.
• Confirm with price action, not the chain alone, before entering.
• Fix a hard stop loss in rupees and size the lots around that loss, not the hoped gain.
• Log the trade with entry, exit, OI read and result so you can review what actually worked.

Sources and further reading

For live data and current contract specifications, use the official NSE Option Chain and NSE India. For free education on options Greeks and writing, Zerodha Varsity is a solid reference. Always confirm the current lot sizes, STT rates, expiry days and margin rules on the official source before you trade, because SEBI and the exchanges revise these regularly. This page is educational and not investment advice.

Sources and Further Reading

For authoritative data and further reading on this topic, refer to NSE Option Chain, NSE India and Zerodha Varsity. Always confirm current rules, rates and contract specifications on the official source before you trade.