Options Contract
An options contract gives the buyer the right, but not the obligation, to exchange an underlying asset at a specified strike price before or on expiry. On NSE, index options on Nifty 50 and Bank Nifty were among the most actively traded derivatives globally by contract volume.
Options contracts are asymmetric instruments: the buyer pays a premium upfront and gains the right to exercise, while the seller (writer) collects the premium and bears the obligation if the buyer exercises. This asymmetry means the buyer's maximum loss is the premium paid, whereas the writer's loss can be substantially larger, particularly for naked call writing.
NSE introduced weekly expiry options on Bank Nifty in 2016 and subsequently on Nifty 50, which dramatically increased the volume and participation in short-dated options. By 2023, NSE's index options segment ranked among the highest in the world by number of contracts traded. Weekly expiries meant that time decay (theta) accelerated sharply in the final two days before expiry, creating distinct dynamics compared with monthly options.
Options contracts are classified by exercise style. NSE index options are European-style, meaning they can only be exercised at expiry, not before. Stock options on NSE are American-style, allowing early exercise at any time before expiry. This distinction matters for pricing models — European options are typically valued using the Black-Scholes framework, while American options require binomial or numerical methods to account for early exercise.
A frequent misconception among new participants is treating options as lottery tickets due to their low absolute premium cost. A Nifty out-of-the-money option might cost ₹10–₹50 per unit, making a single lot appear inexpensive in rupee terms. However, the probability of such options expiring worthless has historically been high, particularly for far out-of-the-money strikes in the final week of expiry. Premium erosion through theta can wipe out a position even if the underlying moves modestly in the anticipated direction.
Options pricing depends on six primary inputs: underlying price, strike price, time to expiry, risk-free interest rate, dividends, and implied volatility. Of these, implied volatility is the only variable that is not directly observable and must be inferred from market prices, making it the most actively traded dimension of the options market. Understanding how each input affects the option premium through the Greeks is essential before engaging with options strategies.