Contents
Definition
Expiry (also: expiration date or last trading day) is the final day on which a futures or options contract can be traded. At expiry, open positions are settled — either through cash payment (index derivatives) or physical delivery of shares (single-stock derivatives) — and the contract is extinguished. If an option buyer does not exercise or close an ITM position, the exchange auto-exercises it at expiry settlement price; OTM options expire worthless. In India, the standard expiry for equity derivatives on NSE/BSE is the last Thursday of the contract month. Source: NSE — F&O Contract Specifications; SEBI Circular on Derivatives Framework (Nov 2024).
Weekly vs Monthly Expiry
India's F&O market distinguishes two expiry cadences:
- Monthly expiry (M, M+1, M+2): All single-stock futures and options expire on the last Thursday of each of three calendar months listed simultaneously. This has been the structure since equity derivatives were introduced in 2000.
- Weekly expiry (index options only): NSE introduced weekly Nifty 50 options in 2019 and Bank Nifty weekly options in subsequent years. These expire every Thursday. Weekly expiry dramatically increased volumes (and retail participation) through zero-day-to-expiry (0DTE) trading.
- SEBI Nov 2024 weekly-expiry uniformity circular: Responding to its July 2024 finding that 93% of individual F&O traders lost money, SEBI restricted each exchange to a single weekly-expiry index. NSE retained weekly Nifty 50 (Thursdays); BSE retained weekly Sensex (Fridays). Bank Nifty, Nifty Financial Services, and Nifty Midcap Select weekly contracts were discontinued — only monthly expiry (last Thursday/Wednesday) remains for these.
Market Mechanics Near Expiry
Expiry day and the days immediately preceding it exhibit distinctive market behaviour:
- Gamma explosion: For ATM options, gamma (rate of change of delta) increases sharply as expiry approaches — a small move in the underlying can shift the option's delta dramatically, creating large P&L swings.
- Theta acceleration: Time value decays fastest in the last 2–5 trading days. An ATM option with ₹100 of time value 7 days before expiry may lose ₹30–40 in the final 2 days.
- Rollover activity: Futures holders who want to maintain exposure close the expiring near-month contract and open M+1. This creates systematic selling pressure on near-month and buying pressure on the next month near expiry.
- Settlement price: For index futures/options: closing value of the index on expiry day. For single-stock: closing price of the share on expiry day. Auto-exercise threshold for NSE index options: in-the-money by any amount.
- F&O ban period: If a stock's OI exceeds 95% of MWPL, it enters ban — no fresh positions allowed until OI falls below 80% of MWPL. Often happens near expiry due to rollover dynamics.
Risk Profile
Expiry mechanics create distinct risks:
- 0DTE (zero days to expiry) options are among the riskiest instruments in listed derivatives — they have very low absolute premium but gamma is near-infinite, meaning small underlying moves produce outsized P&L changes. SEBI's 2024 retail study found that same-day expiry trading (primarily in weekly Nifty options) accounted for a disproportionate share of retail losses. The Nov 2024 circular restricting weekly expiry to one benchmark index per exchange was directly targeted at reducing 0DTE speculative activity.
- Physical delivery risk (single-stock): Options or futures that expire ITM result in mandatory delivery. Buyers of ITM single-stock calls must pay the full contract value (strike × lot size) for share delivery; sellers must provide shares. Failure triggers auction penalty charges by the exchange.
- Pin risk: If spot closes exactly at or near the strike, uncertainty about whether the option is ITM or OTM creates settlement uncertainty — partially mitigated by NSE's 0.01% auto-exercise threshold.
Worked Example
It is Thursday, expiry day. Nifty 50 is at 24,480 at 3:29 PM. A trader holds:
- Long 1 lot Nifty 24,500 Call (ATM, ₹35 premium paid). With spot at 24,480, the call is OTM (spot < strike). If the market closes below 24,500, this expires worthless: full ₹875 (₹35 × 25) lost.
- Long 1 lot Nifty 24,200 Put (OTM at ₹80 premium paid, strike below current spot of 24,480). The put is OTM; full ₹2,000 loss if spot stays above 24,200.
Sudden 3:29 PM drop to 24,350: the 24,500 Call is still OTM (worthless). The 24,200 Put is still OTM at 24,350. Both positions expire worthless despite the market having moved. This illustrates that OTM put buyers require the move to exceed the entire distance to strike, not merely a directional shift.
Caveats
- If your broker's system auto-exercises ITM options and you have not maintained adequate margin for physical delivery, you may receive a margin call on expiry day — check broker notifications in advance.
- Last-Thursday expiry occasionally falls on a NSE holiday; in this case, expiry moves to the preceding Wednesday — always verify the actual expiry date on NSE's holiday-calendar page.
- Rollover costs (basis between near and next month) are not fixed — they widen when cost-of-carry is high (high interest rates) and narrow or go negative in dividend-heavy months.
See Also
Primary Source
NSE — Equity Derivatives Contract Specifications; SEBI Circular on Derivatives Framework — Weekly Expiry Uniformity (Oct 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.