How to read an option chain: a Nifty example for beginners

What an option chain shows

An option chain is a table of all the option contracts on one underlying (say Nifty 50) for one expiry date. Each row is a strike price. The columns on the left describe the call option at that strike, the columns on the right describe the put, and the strike sits in the middle. The current index level is usually marked so you can see which strikes are near the market.

Reading a chain quickly lets you answer three questions: what an option costs, how actively it trades, and where other traders have built positions.

Calls, puts and the strike price

A call option gains value when the index rises above its strike; a put gains value when the index falls below its strike. The price you pay for either is the premium, quoted per unit. One contract is one lot, and the lot size is set by the exchange and revised from time to time, so check it on the chain before you calculate a position's cost: premium × lot size × number of lots.

ATM, ITM and OTM

Every strike is described by where it sits relative to the current index level:

• At the money (ATM): the strike closest to the current level. ATM options have the most time value and usually the most trading.
• In the money (ITM): a call below the current level, or a put above it. These have intrinsic value and cost more.
• Out of the money (OTM): a call above the current level, or a put below it. These are cheaper because they are made only of time value, and they expire worthless if the index never reaches them.

The columns, one by one

Brokers and sites order them differently, but the same fields appear everywhere:

• LTP (last traded price): the premium of the most recent trade.
• Change: how far the LTP has moved since the previous close, in rupees or percent.
• Bid and ask: the best price buyers are offering and sellers are asking. A wide gap means a thin market; expect worse fills.
• Volume: how many contracts have traded today.
• OI (open interest): how many contracts are open right now. It rises when new positions are created and falls when they are closed.
• Change in OI: how much open interest has been added or removed today. Often more telling than OI itself.
• IV (implied volatility): the volatility the premium implies. Higher IV means options are priced for bigger moves.
• Greeks: delta (how much the premium moves per point of the index), theta (time decay per day), gamma and vega.

A worked example

Example numbers, not a live quote. Suppose Nifty is at 25,040. The ATM strike is 25,050. The 25,050 call trades at ₹120 and the 25,050 put at ₹110. If you buy one lot of the call, your cost is ₹120 × lot size, plus charges, and that is the most you can lose. You make money at expiry only if Nifty closes above 25,050 + 120 = 25,170 (the breakeven), before charges.

Now look at OI. If the 25,200 call has by far the highest call OI and the 24,800 put has the highest put OI, many traders read 25,200 as a level sellers expect to hold (resistance) and 24,800 as support. These are crowd positions, not guarantees, and they shift during the day.

Common mistakes when reading the chain

• Buying far OTM options because they look cheap. Most of them expire worthless.
• Ignoring the bid-ask spread on illiquid strikes, which can eat your profit on entry and exit.
• Reading OI as a direction signal on its own. A large OI can be hedged positions or spreads.
• Forgetting time decay: an option can lose value even when the index doesn't move.

Questions