A call option is one of the two basic building blocks of the options market. Almost every strategy, however complicated, is built from call options, put options, or both.
This article has the call option explained from first principles: what the buyer gets, what the seller takes on, a worked example with every outcome at expiry, what happens before expiry, and the common uses and mistakes.
What a call option is
A call option gives the buyer the right, but not the obligation, to buy an underlying at a fixed price — the strike price — at expiry. In India, options are European-style, so this right applies at expiry.
The buyer pays a price for this right, called the premium. The seller receives the premium and takes on the obligation to sell at the strike if the buyer exercises.
A buyer of this contract benefits if the underlying rises above the strike by more than the premium paid. The seller benefits if it does not.
For index options, settlement is in cash: instead of delivering the index, the difference between the final settlement price and the strike is paid. For stock options, settlement is by delivery of shares.
Premiums are quoted per unit and multiplied by the lot size set by the exchange. The examples below are per unit.
A worked example
Suppose an index is at 24,000. A trader expects it to rise over the next two weeks and buys a 24,100 strike call option expiring in two weeks, at an illustrative premium of 120.
Cost: 120 per unit. This is the most the buyer can lose.
Breakeven at expiry: strike plus premium, 24,100 + 120 = 24,220. The index must finish above this for the trade to profit.
Outcomes at expiry:
Index at 23,800: the option expires worthless. Loss: 120.
Index at 24,100: still worthless, since there is no value at the strike. Loss: 120.
Index at 24,220: the option is worth 120. Result: breakeven.
Index at 24,400: worth 300. Profit: 300 − 120 = 180.
Index at 24,600: worth 500. Profit: 380.
The pattern: a fixed, limited loss below the strike, and a profit that grows point for point above the breakeven, without a ceiling.
Notice that the index can rise from 24,000 to 24,200 — the buyer's view was correct — and the trade still loses, because the rise did not exceed the breakeven. Direction alone is not enough; the size of the move matters.
The seller's side
Every buyer has a seller. The seller of the same 24,100 call option receives 120 and takes on the obligation.
If the index finishes at or below 24,100, the option expires worthless and the seller keeps the full 120.
If it finishes at 24,220, the seller breaks even.
If it finishes at 24,600, the seller loses 500 − 120 = 380.
The seller's profit is capped at the premium, while the potential loss grows without limit as the index rises. That is why selling this contract without protection requires substantial margin and careful risk control, and why many sellers combine it with another option to cap the loss, forming a spread.
Before expiry: what moves the price
Most option positions are closed before expiry, so the premium's behaviour along the way matters as much as the expiry outcome.
The underlying's price. As the index rises, the premium usually rises. How much depends on delta: an option near the money might gain roughly half a point for each point the index rises.
Time. Every day, some time value disappears. If the index does nothing, the premium falls, slowly at first and faster near expiry.
Volatility. If the market expects bigger moves, implied volatility rises and the premium rises with it, even with the index unchanged. After events, it often falls.
So a buyer can be right about direction and still see the premium fall, if the move is slow or volatility drops. A buyer who expects a move within days should choose an expiry that gives the view enough time.
Buying a call versus buying the underlying. Someone expecting a rise could instead buy the shares, or a futures contract. Buying shares needs the full price but carries no expiry; the position can be held for years. A futures contract needs margin, rises and falls point for point with the underlying, and can lose far more than the margin if the price falls. A bought call option costs only the premium and cannot lose more than that, but it needs the rise to happen before expiry and by more than the premium. Each suits a different view and a different tolerance for time and loss.
Common uses and mistakes
Uses: a defined-risk way to express a rising view; part of spreads that reduce cost; and, for sellers, a covered call against shares already held.
Mistakes beginners make:
Buying far out-of-the-money contracts because they are cheap. They need a large move and usually expire worthless.
Ignoring the breakeven. Being right about direction is not enough if the move is smaller than the premium.
Holding into the final days hoping. Time decay is fastest at the end.
Selling without protection. The seller's loss is open-ended.
Forgetting the lot size. A premium of 120 is multiplied by the lot, which can mean a substantial rupee amount.
An account with an option chain and payoff view
See premiums, breakevens and payoffs before placing anything. Free to open
Prices in the example are illustrative, not market data. Lot sizes, settlement rules and margins are set by the exchanges and SEBI and change from time to time. This is educational material, not advice, and no position is recommended. We run no tips group and no signal service, we manage nobody's money, and no return is promised. Bought options frequently expire worthless, and sold options can lose more than the amount blocked against them.
Disclosure: the account-opening link on this page is under Atul Shrivastava's Zerodha Authorised Person registration (NSE AP Reg: AP2516003481; Zerodha Broking Ltd. SEBI Reg: INZ000031633) and earns a revenue share. TheFinBaba is not a SEBI-registered Investment Adviser — this content is educational, not investment advice.
Frequently Asked Questions
What is a call option in simple words?
A contract giving the buyer the right, but not the obligation, to buy an underlying at a fixed strike price at expiry, in exchange for a premium paid to the seller.
How do I calculate the breakeven of a call option?
Add the premium paid to the strike price. A 24,100 strike bought for 120 breaks even at 24,220 at expiry.
What is the maximum loss when buying a call option?
The premium paid, multiplied by the lot size.
Why did my call option lose money even though the market went up?
Because the rise was smaller than needed to exceed the breakeven, or time decay and falling volatility reduced the premium faster than the move added to it.
What is the risk of selling a call option?
The seller's profit is limited to the premium, but the loss grows without limit as the underlying rises, unless the position is protected.
Related Reading
- The put option, the other building block
- Combining both into an iron butterfly
- The payoff line of a bought call
- Selling against shares you hold
- What the premium is made of
- Learning options before trading them
Disclaimer: TheFinBaba provides educational content only - this is not investment advice. Trading involves risk of loss.
