Expiry Day
Expiry day is the final day on which a futures or options contract for a given expiry series is valid and must be settled — either through cash settlement (for index derivatives) or delivery (for certain stock futures and options) — after which the contract ceases to exist.
In the Indian derivatives market, futures and options contracts had a defined life cycle. Each contract series had a specific expiry date, at which point it ceased to be tradeable and all open positions were compulsorily settled. For monthly contracts, expiry historically fell on the last Thursday of the calendar month. For weekly contracts, expiry occurred every Thursday. If Thursday was a public holiday, the expiry was moved to the immediately preceding trading day.
On expiry day, several distinct dynamics unfolded in the derivatives market. Traders who held open futures positions were required to either square off their position before market close or allow settlement at the final settlement price — for index futures, this was based on a volume-weighted average price of the index's underlying stocks during the last 30 minutes of trading. For stock futures, physical delivery had been mandated by SEBI for stocks in the 'compulsory physical delivery' list, meaning holding open stock futures positions to expiry resulted in the obligation to give or take delivery of shares.
Options contracts that expired in-the-money (ITM) were automatically exercised by the clearing corporation, while those expiring out-of-the-money (OTM) expired worthless. Options sellers who had collected premiums for OTM contracts saw those contracts expire and become zero value — the premium collected became profit. Options buyers who held OTM contracts to expiry saw their entire premium investment reduce to zero. This asymmetry made expiry day particularly important for options strategies, as the final hours frequently saw accelerated time decay and unpredictable volatility.
The last few hours of expiry day were historically among the most volatile trading periods in the Indian market. Large institutional players, proprietary trading desks, and algorithmic traders all managed rollovers (closing current-month positions and opening next-month positions) simultaneously, creating significant order flow concentration. Retail traders who were unfamiliar with expiry mechanics and held leveraged derivatives positions frequently experienced unexpected P&L swings on these days.
Post-2019, as weekly options gained dominance in trading volumes — particularly Nifty 50 and Bank Nifty options — the significance of the Thursday expiry became far more frequent, with the market effectively having a major expiry event every week rather than once a month.