📬 Exercise, assignment and expiry day in India

🎯 In 30 seconds: Indian options are European style: the right is used only at expiry, and NSE exercises every in-the-money option automatically. Exercised options are assigned to sellers at random. Index options settle in cash against the index's official settlement price. Stock options settle by delivery: the call buyer must pay for the full lot and receive shares, the put buyer must deliver them. Because delivery needs real money or shares, brokers raise margins on these positions through expiry week. Exercise attracts STT of 0.15% of the intrinsic value, paid by the buyer (rate from 1 April 2026). The settlement price method changes on 7 December 2026.

Two words, two sides

Exercise is what the buyer of an option does: use the right. Assignment is what happens to a seller: they are picked to meet the obligation. In India you rarely do either by hand. The clearing corporation does both, automatically, at the end of expiry day.

Think of a dabbawala network. You never hand your tiffin to a particular person at the other end. You put it into the system, and the system makes sure it reaches someone on the right route. Options exercise works the same way. The buyer's in-the-money position goes into the clearing system, and the system matches it to a seller of the same option, chosen at random.

European style: exercise only at expiry

NSE's settlement rules say that for index options and options on individual securities, "exercise style is European style" and "final exercise is automatic on expiry of the option contracts". In practice:

• You can trade an option (buy it or sell it) at any time during market hours until it expires.
• You cannot exercise it before expiry. There is no early exercise and so no early assignment, unlike most US stock options.
• At expiry, every option that is in the money at the settlement price is exercised. Options at or out of the money simply expire worthless.
• Long in-the-money positions are assigned to short positions in the same series at random.

For stock options, there used to be a "do not exercise" choice for strikes close to the money. Press reports from March 2023 say NSE withdrew that facility for stock options, so in-the-money stock options now go to delivery unless closed before the end of expiry day. Check your broker's current policy before relying on any exception.

Index options: settled in cash

You cannot deliver "the Nifty", so index options settle in money. Hypothetical:

• You hold one lot of the Nifty 24,000 call, bought at 150 (₹9,750). Lot size 65.
• On expiry day the official settlement price of the Nifty is 24,180.
• The call is 180 points in the money. You receive 180 x 65 = ₹11,700. The seller assigned to you pays ₹11,700.
• Your profit: ₹11,700 - ₹9,750 = ₹1,950, before brokerage and other charges.
• STT on exercise: 0.15% of the intrinsic value of ₹11,700 = ₹17.55, paid by you as the buyer.

NSE says final settlement amounts for options are credited or debited to clearing members on the day after expiry, so the money reaches your trading account from your broker after that.

How the settlement price is set, and the December 2026 change

The settlement price decides who is in the money. It is not the last traded price of the option. It is a price for the underlying set by the exchange and clearing corporation.

From 3 August 2026 to 6 December 2026. Under SEBI's circular of 16 January 2026, the cash market has a Closing Auction Session for shares that have derivatives, and the closing price comes from that auction. The equity derivatives segment trades until 3:40 pm. The settlement price of an index option is the index's closing price on expiry day, built from its shares' closing prices. For stock derivatives, it is a volume-weighted average of the share's closing prices across exchanges.

From 7 December 2026. SEBI's circular of 15 October 2026 changes this:

• The Closing Auction Session moves to 3:30 pm to 3:40 pm.
• Expiring index derivatives stop trading at 3:30 pm on expiry day. Other index derivatives, and all stock derivatives including those expiring, trade until 3:45 pm.
• Index settlement price: the index value calculated from the volume-weighted average prices (VWAP) of its shares in the last 30 minutes of continuous trading. Exchanges must publish an indicative value in real time during those 30 minutes.
• Stock settlement price: the share's VWAP in the last 30 minutes of continuous trading, across all exchanges, with an indicative value shown in real time.

What this means for you: on expiry day, your option's final value is set by a price you can watch build up during the last half hour. A sharp move in that window can flip an option from in to out of the money. These timings changed twice in 2026, so check the exchange's current circulars before relying on any clock time.

Stock options: settled by delivery

Since SEBI moved stock derivatives to physical settlement in stages between 2018 and October 2019, every stock option that ends in the money is settled by delivery of shares. Hypothetical Sharma Foods Ltd, lot of 1,000 shares (real lots are set by the exchange), settlement price ₹1,560:

Settlement happens a short time after expiry on the clearing corporation's published schedule. If you do not have the shares to deliver, the delivery fails. NSE Clearing runs an auction for shortfalls in physically settled derivatives, and the defaulting side bears the cost and penalties. If you do not have the money to pay for shares you must receive, your broker will have collected margin earlier and may close your position before expiry. Short selling in India covers auctions in the cash market.

The margin build-up in expiry week

To make sure everyone can pay or deliver, the clearing corporation charges delivery margin on stock derivative positions that are headed for delivery, starting a few days before expiry. Under NSE Clearing's circular of 17 January 2020 (still the latest schedule this course found as of October 2026), the share of the full delivery margin charged at the end of each day is:

On top of the clearing corporation's levy, most brokers set their own, stricter rules: higher margins earlier, blocks on new positions in expiry week, or forced square-off of in-the-money stock options at a set time on expiry day. If you hold a long in-the-money stock call on the day before expiry and have only the premium in your account, expect a margin call or an automatic square-off.

The practical rule for beginners: if you do not intend to buy or sell the shares, close stock options before the delivery margins start.

Expiry day itself

Expiry day concentrates risk in a few hours. Several SEBI rules apply only on that day, from the circular of 1 October 2024:

• Extra margin on short options: an additional extreme loss margin of 2% on short index options expiring that day, from 20 November 2024.
• No calendar spread benefit: positions that offset each other across expiries do not get reduced margin on the day one leg expires, from 1 February 2025. A short weekly call hedged with a long monthly call is margined as if unhedged on the weekly expiry day.
• Intraday checks on position limits: exchanges take at least four random snapshots a day of index derivative positions, from 1 April 2025.

Two expiry-day situations catch people out:

• Pin risk on stock options. If the share closes very near the strike, you cannot be sure until the settlement price is out whether your option will be exercised. A seller may or may not end up delivering shares. Closing the position before the final half hour removes the doubt.
• Fast-moving cheap options. An OTM option worth 2 points at 2 pm can be worth 60 points at the close, or zero. Sellers who leave short options open until the end face the largest swings. See Managing options risk.

Other things that can happen

• Corporate actions. When a company declares a bonus issue, a split, a rights issue or a large special dividend, the exchange adjusts the strike and lot of its options so the position's value is not unfairly changed. The new terms appear in exchange circulars. See Dividends, bonus issues, splits and buybacks.
• F&O ban. When open interest in a stock crosses the market-wide limit, new positions are blocked until it falls; you can only reduce. A ban in expiry week makes it harder to roll. The rules every Indian trader runs into has the details.
• Holidays. If expiry falls on a trading holiday, NSE's contract terms move it to the previous trading day.
• Tax. F&O gains and losses are generally treated as business income, not capital gains. See Taxes for traders and investors, and check with a chartered accountant.

Try it

Find your broker's written policy on physical settlement of stock derivatives (usually in the help or support section). Write down three things: from which day they start blocking or charging extra margin on in-the-money stock options, at what time on expiry day they square off positions without enough margin, and what they charge if they do. Then pick one stock with options on NSE and, for its next monthly expiry, compute what you would owe if you held one in-the-money call to expiry: strike x lot size. Compare that with the money in your trading account.

Sources

• NSE: Equity derivatives settlement mechanism
• SEBI: Introduction of Closing Auction Session in the equity cash segment, circular of 16 January 2026 (PDF)
• SEBI: Review of the Closing Auction Session, market timings and settlement methodology for derivatives, circular of 15 October 2026
• NSE Clearing: Delivery margins for delivery settlement in equity derivatives, 17 January 2020 (PDF)
• NSE Clearing: Settlement schedule for physical settlement in equity derivatives, including auction, September 2019 (PDF)
• NSE: Revision of settlement mechanism in equity derivatives (physical settlement), 23 April 2018 (PDF)
• SEBI: Measures to strengthen equity index derivatives framework, 1 October 2024
• NSE: Changes in rates of Securities Transaction Tax, 31 March 2026 (PDF)
• Outlook Business: NSE to discontinue do not exercise facility for stock options (March 2023)