Exercise
Exercise is the act by which an options buyer invokes their right to buy (call) or sell (put) the underlying asset at the predetermined strike price, triggering the assignment process for the option writer.
Exercising an option was the fulfilment of the contract from the buyer's perspective. A call option buyer who exercised was invoking the right to purchase the underlying at the strike price; a put option buyer who exercised was invoking the right to sell the underlying at the strike price. For exercise to be economically rational, the option must have intrinsic value — that is, it must be in-the-money. Exercising an out-of-the-money option would result in an immediate loss relative to simply allowing the option to expire worthless.
On NSE, all options — both equity and index — were European-style, which meant the holder could only exercise at expiry and not before. This differed from American-style options (prevalent in US markets) where the buyer could exercise at any point. The European structure simplified the exercise decision: if an NSE option was in-the-money at expiry, it was automatically exercised by the exchange on the holder's behalf. A Nifty call with a 22,000 strike and Nifty settling at 22,300 would be automatically exercised, crediting the holder with the Rs 300 intrinsic value multiplied by the lot size.
Auto-exercise by NSE's clearing corporation (NSCCL) was a safeguard that ensured in-the-money options at expiry were not accidentally allowed to lapse. Prior to formal auto-exercise rules, there were instances of traders failing to exercise profitable options, particularly in volatile or confused end-of-day markets. The automation removed this operational risk for index options but required that traders be aware of the physical delivery implications for stock options, where auto-exercise triggered actual share transfers.
The decision to exercise early was irrelevant in the Indian market given European-style options, but traders sometimes confused early exercise with the option to close (square off) a position before expiry. Closing a position by selling the option in the secondary market was distinct from exercising — it allowed the holder to capture both intrinsic and remaining extrinsic value, whereas exercise at expiry yielded only intrinsic value. For this reason, standard practice on NSE was to sell in-the-money options in the market before expiry rather than wait for auto-exercise, extracting any residual time value that remained.
For stock options subject to physical settlement, a trader who held in-the-money calls through expiry received shares debited to the option writer's demat account and credited to their own. Conversely, exercised in-the-money put holders were required to deliver shares and received cash. This physical dimension meant that participation in stock options through expiry required not just capital but also demat infrastructure and an understanding of the delivery obligation calendar.