Exercise vs Assignment vs Expiry in Indian Options
Exercise is the option buyer’s right being used. Assignment is the option seller being handed the matching obligation. Expiry is the date the contract stops existing. Three different events, and in Indian markets all three happen on the same day because our options are European style.
Getting these mixed up is expensive. A trader who leaves an in the money stock option open at expiry can end up with a delivery obligation running into lakhs of rupees, on a position that was meant to be a small premium bet.
The Three Events, Defined Precisely
- Exercise: the buyer converts the option into a settlement outcome. Since Indian options are European style, this happens only at expiry.
- Assignment: the clearing corporation allocates the exercise to a seller of the same contract. The seller has no say in it.
- Expiry: the contract’s last day. In the money contracts settle, out of the money contracts lapse worthless.
The phrase American style gets thrown around in Indian trading groups. It does not apply here. NSE moved stock options to European style years ago, so early exercise is off the table.
How Settlement Actually Works
| Feature | Index options | Stock options |
|---|---|---|
| Style | European | European |
| Settlement | Cash | Physical delivery of shares |
| What you receive | Rupee difference | Shares, or an obligation to deliver them |
| Funds needed at expiry | None beyond the position | Full contract value or the shares |
| Main expiry risk | Adverse settlement price | Delivery you cannot fund |
For Nifty and Bank Nifty options, settlement is in cash against the final settlement price of the index. Nothing is delivered. If you hold a 24,000 Nifty call and the index settles at 24,180, you receive 180 points times the lot size, less charges.
Stock Options Settle Physically
This is the part that surprises people. Every in the money single stock option in Indian markets goes to physical settlement through NSE Clearing.
Take a stock at Rs 1,450 with a lot size of 500 shares. You bought one 1,400 call at a premium of Rs 30, an outlay of Rs 15,000. At expiry the stock closes at Rs 1,450, so the option is Rs 50 in the money and is exercised. You must now pay 500 x 1,400, or Rs 7,00,000, and take delivery of 500 shares. Your broker demands that money, plus STT on the intrinsic value.
Close to Money and the CTM Rule
Exchanges apply a close to money, or CTM, rule to protect traders from a specific trap. Options that are only marginally in the money can be worth less than the transaction costs of settling them.
Under the rule, a defined number of strikes closest to the settlement price on the in the money side count as CTM. Unless the buyer gives a contrary instruction to their broker, those contracts lapse instead of being exercised. The strike count and the instruction deadline are set by exchange circular and change from time to time, so check the current NSE notification.
Deep in the money contracts are always exercised. CTM does not save you there.
The Trap That Catches Retail Traders
Here is the sequence that goes wrong:
- A trader buys a cheap in the money or near the money stock call for a few thousand rupees.
- Expiry day arrives and the option finishes in the money.
- The contract is auto exercised. The trader is now obliged to buy shares worth several lakh.
- The account does not have that money, so the trade becomes a short delivery or a margin default.
- Penalties, auction settlement of the shortfall and possible square off follow.
Brokers manage this by blocking physical delivery margins through expiry week, stepping up across the last four sessions. Many also square off unhedged stock option positions on expiry day if funds are not arranged, which protects you at whatever price the market offers.
The safe habit is to close single stock option positions before the delivery margin cycle begins, or to hold the funds to settle. Never assume an in the money option pays out cash the way an index option does.
Frequently Asked Questions
Can an option seller be assigned before expiry in India?
No. All listed Indian equity and index options are European style, so assignment can only occur at expiry. Traders who read American style material online often worry about early assignment unnecessarily.
What happens if my option expires exactly at the money?
An option at the strike has no intrinsic value, so it lapses worthless. Strikes very near the settlement price may also fall under the CTM rule and lapse rather than settle.
Do I pay STT on an exercised option?
Yes, and the rate on exercised options differs from the rate on an ordinary option sale. It applies to intrinsic value, which is why letting a barely in the money option settle can cost more than it earns. Check the current rate schedule.
Does physical settlement apply if I hold a hedged spread?
Both legs are treated separately at expiry, so a spread where one leg is in the money and the other is not can still produce a delivery obligation. Margins are lower for hedged positions, but the settlement mechanics do not disappear.
Key Takeaways
- Exercise is the buyer’s right, assignment is the seller’s obligation, expiry is the date both crystallise.
- Indian index and stock options are European style, so there is no early exercise.
- Index options settle in cash, single stock options settle by physical delivery of shares.
- CTM rules let marginally in the money contracts lapse, but deep in the money ones are always exercised.
- An unfunded in the money stock option turns into a delivery obligation with penalties attached.
