Contents
Definition
A call option is a derivative contract that grants the buyer the right — but not the obligation — to purchase a specified underlying asset (an equity share, index, commodity, or currency) at a pre-agreed strike price on or before the expiry date, in exchange for an upfront payment called the premium. The seller (writer) of the call receives the premium and is obligated to sell if the buyer exercises. In India, equity call options are European-style for indices (exercise only at expiry) and American-style for individual stocks (exercise any time up to expiry), though physical exercise before expiry is rare for single-stock contracts given they are now physically settled. Source: SEBI — Securities Contracts (Regulation) Act and NSE F&O contract specifications.
How It Is Priced
Call option premium has two components:
- Intrinsic value = max(Spot − Strike, 0). A call is in-the-money (ITM) when spot > strike. Out-of-the-money (OTM) calls have zero intrinsic value.
- Time value = Total premium − Intrinsic value. Time value reflects the probability of the option moving into profit before expiry, priced by the Black-Scholes model (or binomial model for American-style). Key inputs: spot price, strike price, time to expiry, risk-free rate, and implied volatility (IV).
The primary Greeks relevant to call buyers:
- Delta: Rate of change of option price per ₹1 move in underlying. ATM call delta ≈ 0.5; deep-ITM ≈ 1; deep-OTM ≈ 0.
- Theta (time decay): Value lost per calendar day as expiry approaches. Accelerates non-linearly in the final 2 weeks. An ATM option may lose 5–10% of its premium value per day in the last 5 days.
- Vega: Sensitivity to implied volatility. A 1% rise in IV increases the premium of an ATM call.
Market Mechanics
- Settlement: Index calls (Nifty, Bank Nifty) — cash settled at expiry. Single-stock calls — physically settled at expiry if exercised ITM.
- Lot size: Same as futures. Nifty 50: 25 units; Bank Nifty: 15 units (2024 norms).
- STT: 0.0625% of option premium on buy side. On exercise (ITM at expiry): 0.125% of intrinsic settlement value on the exercised contracts.
- Margin for sellers (writers): Naked call writing requires SPAN + exposure margin (substantially higher than buying, since the seller's loss is unlimited). Covered calls — selling calls against an existing stock position — have lower margin requirements.
Risk Profile
For the buyer: maximum loss is structurally limited to the premium paid — this is a factual feature of the instrument. However, losing 100% of premium is a frequent outcome for OTM call buyers: SEBI's July 2024 retail F&O study found that among individual options buyers, 89% incurred net losses over FY22–FY24, with a significant proportion experiencing complete premium loss on OTM positions. Leverage amplifies both gains and losses — a 2% move in Nifty can double or zero an ATM call premium over a week. For the seller (writer): profit is capped at the premium received; loss is theoretically unlimited if the underlying rallies sharply. Uncovered call writing requires significant margin and carries unbounded risk.
Worked Example
Nifty 50 is at 24,500. A trader buys 1 lot of the 25,000 Call (OTM, 500 points away) expiring in 28 days, at a premium of ₹110/unit. Total outlay: ₹110 × 25 = ₹2,750. Break-even at expiry: 25,000 + 110 = 25,110 (Nifty must rise 2.5% for break-even).
Scenario A: Nifty rises to 25,400 at expiry. Intrinsic value = 25,400 − 25,000 = ₹400. P&L = (400 − 110) × 25 = ₹7,250 gain (263% return on ₹2,750 outlay).
Scenario B: Nifty stays at 24,600 at expiry. Call expires OTM; loss = ₹2,750 (100% of premium). The 2% Nifty gain was insufficient to offset the OTM position.
This illustrates why time decay and strike selection are decisive for options buyers.
Caveats
- Buying multiple cheap OTM calls ("lottery tickets") is among the most common and consistently loss-making retail patterns identified in SEBI's 2024 study.
- IV expansion at volatile periods inflates premiums — buying calls during high-IV periods means paying for expected volatility that may not materialise (vol crush after events like RBI policy, earnings).
- For physically settled single-stock calls that expire ITM, failure to maintain cash for delivery can result in auction penalties via the exchange.
See Also
Primary Source
NSE — Equity Options Contract Specifications; SEBI Study on F&O Retail Participation, July 2024
MintByte (ARN-314872 / APMI APRN-01658) provides this glossary for educational purposes only. Nothing here constitutes investment advice, a recommendation to buy or sell any security, or a guarantee of returns. Equity and derivatives trading involves risk of loss. Consult a SEBI-registered adviser before making investment decisions.