Expiry Day Options Trading: The Risks and Realities

Expiry day options trading means buying or selling contracts on the day they settle, when time value is nearly gone and swings per rupee of premium are at their most violent. Premiums are cheap and moves are fast, which is both the attraction and the reason accounts drain. On expiry day an option’s price is almost entirely intrinsic value, so it stops behaving like a slow-decaying asset and starts behaving like a geared bet on the next few index points.

There is also a settlement cost most beginners never see coming, where a profitable option hands you a net loss.

Covered here: what changes on the final day, the STT trap with the arithmetic spelt out, how the settlement price is fixed, and a checklist.

What actually changes on the last day

Time value goes to zero

Premium is intrinsic value plus time value, and by the final session time value has nothing left to give. An out-of-the-money option is a lottery ticket with hours on the clock. If the index does not come to it, premium goes to zero. Not close to zero. Zero. See how theta decay eats premium.

Gamma turns small moves into large ones

Delta stops behaving gently. A strike at the money can go from acting like half a lot of the index to a full lot within minutes. That is high gamma, and why an option that cost Rs 8 trades at Rs 45 and back to Rs 3 inside an hour.

Liquidity concentrates and then evaporates

Volume piles into the two or three strikes nearest spot. Everything else widens out. In the last twenty minutes, spreads on far strikes get wide enough that exiting costs more than the position is worth.

The STT trap: when a winning option loses money

Securities transaction tax works differently depending on whether you sell the option or let it get exercised. Rates from 1 April 2026:

Event	STT rate	Charged on	Paid by
Sale of an option (squaring off)	0.15%	Premium value	Seller of the option
Option exercised or assigned at expiry	0.15%	Settlement value, meaning intrinsic value	Buyer of the option
Futures	0.05%	Contract value, sell side	Seller

Read the second row again. On exercise, 0.15% applies to settlement value, not premium. A far larger base.

Worked example with real numbers

Suppose you buy one lot of a Nifty 25,000 call at a premium of Rs 30, with a lot size of 75. Cost is 30 multiplied by 75, or Rs 2,250. On expiry the index settles at 25,020, so the option is Rs 20 in the money.

Path 1, you square off before the close at Rs 20.

• Sale proceeds: 20 multiplied by 75 equals Rs 1,500.
• STT: 0.15% of Rs 1,500 equals Rs 2.25.
• Net loss on the trade: about Rs 752 before brokerage.

Path 2, you let it expire and it gets exercised.

• Settlement credit: intrinsic value of 20 multiplied by 75 equals Rs 1,500.
• Settlement value for STT: 25,020 multiplied by 75 equals Rs 18,76,500.
• STT: 0.15% of Rs 18,76,500 equals Rs 2,814.75.
• You are Rs 1,314.75 down on settlement alone, so the total loss is about Rs 3,565.

Same market outcome. A gap of roughly Rs 2,812 caused purely by whether you clicked exit. Not superstition, arithmetic.

How is the expiry settlement price decided?

Not by the option’s last traded price, and not by the closing tick of the index. The exchange computes a final settlement price for the underlying from trading in the last part of the session, using a weighted average rather than a single print. Pushing a contract across a strike with one large closing order is therefore very hard.

The exact window and method sit in the exchange’s contract specifications and do get revised, so confirm the current definition on the NSE contract specifications page.

Two related facts. Index options in India are cash settled, and NSE options are European style, exercisable only at expiry. There is no early assignment risk on an Indian index option.

Why do most expiry day option buyers lose money?

Because they are buying an asset guaranteed to decay to a known number within hours, and they need direction, size and timing all correct.

Three patterns repeat. Buying far out-of-the-money strikes because Rs 4 “cannot lose much”, then watching the premium vanish. Averaging down as premium falls, adding size with less time to recover. And holding into the last thirty minutes, when the spread has already made a clean exit impossible.

Sellers are not safe either. Naked selling looks like easy premium until a sharp move arrives and margin expands mid-session. The recurring errors are listed in common options trading mistakes.

Stock options are physically settled, and that is a different problem

Stock futures and stock options in India are physically settled. Hold an in-the-money stock option to expiry and there is no cash difference to collect. You must take delivery of shares, or deliver them.

For one lot of a Rs 3,000 share with a lot size of 250, that is an obligation of 3,000 multiplied by 250, or Rs 7,50,000. Brokers raise margin sharply before expiry, and many square off clients if the funds are missing. Short positions carry the mirror image, covered in assignment risk on short options.

An expiry day checklist

1. Confirm the current lot size and expiry schedule on the exchange website. Both get revised.
2. Fix your maximum loss in rupees first, then size from that number, not from available margin.
3. Trade only strikes with depth on both sides. If the spread is wider than a few percent of premium, skip it.
4. Set an exit time, not just an exit price. Many traders flatten before the final half hour.
5. Square off in-the-money options rather than letting them expire, unless intrinsic value comfortably absorbs the exercise STT.
6. For stock options, close early unless you intend to take delivery and have the cash.

Where the real edge sits

• Defined-risk spreads cap what a gap can do, because the long leg limits the short leg. Naked legs do not.
• Costs matter more than usual. On a Rs 20 premium, brokerage and STT are a big share of the outcome.
• F&O income is non-speculative business income in ITR-3, and losses carry forward 8 years only if you file by the due date.
• Weekly and monthly contracts differ on their last day, compared in weekly versus monthly options.

Risk note: expiry day trading is among the fastest ways to lose capital in Indian markets. As a seller your loss can exceed the premium collected, and margin can be called intraday. Trade small or not at all until you have followed a written plan for months.

Frequently Asked Questions

What happens if I do nothing and my option expires worthless?

You lose the premium you paid, and that is the end of it. No STT applies to an out-of-the-money option at expiry because there is no settlement value. Nothing further is needed from you, and the position clears out after settlement.

Can my broker square off my expiry day position without asking?

Yes. Brokers routinely close client positions near expiry when margin is short, when a delivery obligation cannot be funded, or under their own risk policy. Cut-off times differ by broker, so read that policy before relying on holding to the close.

Is the STT trap avoidable if my option is deep in the money?

Partly. Exercise STT is a fixed 0.15% of settlement value, so the deeper in the money you are, the smaller that charge is relative to your payoff. On a thin in-the-money amount it can swallow the entire profit. Squaring off is still usually cheaper.

Do I need extra margin to hold options on expiry day?

Buyers pay only the premium, so no. Sellers face SPAN and exposure margin set by the clearing corporation, and those can rise intraday as volatility increases. For stock contracts heading into physical settlement, brokers add a delivery margin in the days before expiry.

Which is riskier on expiry day, buying or selling options?

Buying loses more often, since most cheap options expire worthless. Selling loses less often but with a far larger tail, because a sharp move against a naked short can exceed the premium collected several times over. Neither is safe without defined risk.

Key Takeaways

• On expiry day premium is almost pure intrinsic value, so gamma dominates and small index moves cause large swings.
• Exercise STT of 0.15% applies to settlement value, not premium: a Rs 20 in-the-money Nifty option can cost Rs 2,814 on a 25,020 settlement.
• Squaring off before the close is nearly always cheaper than letting a small in-the-money option expire.
• Index options are cash settled and European style. Stock options are physically settled and can create a delivery obligation worth lakhs.
• Confirm lot size and expiry schedule on the exchange site each time, since both get revised.
• Set a rupee loss limit and an exit time before entering, and prefer spreads to naked legs.