How settlement actually works
Indian index options are cash settled. Nothing is delivered. On expiry, an in-the-money option is closed out for its intrinsic value and the money moves; an out-of-the-money option simply ceases to exist and is worth nothing.
That has a consequence most people only half-absorb: on expiry day the premium has nowhere to go except onto the intrinsic line. Every rupee of time value must be gone by the close, and it is not a gradual process on that final day — it is a deadline.
Stock options are different — they are physically settled in India. An in-the-money stock option that you let expire results in actual delivery obligations and a margin requirement that can be many times the premium. If you hold stock options, know this before the final day rather than on it.
The closing price is not the last trade
This catches people every single expiry, and it is entirely avoidable.
Settlement is not based on the last traded price. For index derivatives it is based on the weighted average price over the final half hour of the session. The exchange computes it after the close and publishes it.
The reason this matters: an option a few paise in the money on the last trade can settle out of the money, and the reverse. If your position's outcome depends on a margin that thin, you were never really in control of it — and the honest fix is to close the position rather than to hope the average lands your way.
On expiry day the question stops being "where is it going" and becomes "what will one specific number turn out to be". Those are very different questions to be exposed to.
Why price clusters near strikes
Indices often spend expiry day drifting sideways very close to a round strike, and it looks suspicious to anyone watching for the first time. The mechanism is mundane.
Large participants who have sold options at that strike hold offsetting positions in the underlying, and as expiry approaches the hedging arithmetic requires them to buy when price falls below the strike and sell when it rises above. That is not a conspiracy — it is the mechanical consequence of hedging a short option position as delta swings violently near the strike on the final day.
The practical reading: on expiry day, a strike with very large open interest acts like a magnet, and options at that strike lose value faster than the calendar alone would suggest.
The STT trap
This one costs real money and is almost entirely unknown to newer traders.
Securities Transaction Tax on options is charged at one rate on the premium when you sell a contract, and at a much higher rate on the settlement value when an in-the-money option is allowed to expire.
The difference is not small. An option that finishes barely in the money and is allowed to expire can incur an STT charge larger than the payout it produces — turning a nominally profitable position into a net loss on the ledger.
The rule that follows is simple: close in-the-money option positions before expiry rather than letting them settle, unless you have specifically checked the arithmetic. The brokerage on closing is trivial next to the difference in STT.
Holding a nearly worthless long option "in case it moves" through the final hour. The decay is at its most violent, the delta is at its most unstable, and the settlement is decided by an average you cannot see forming. Deciding to hold is fine. Forgetting to decide is not, and forgetting is what usually happens.
Read it yourself
- What is this chart doing all session, and what is the likely reason?
- A 100 call is trading at 0.45 mid-session. Split that premium.
- Price finishes the last trade at 100.2. Can you say from this chart whether the 100 call settles in the money?
Show answers
1. Pinning. Price oscillates in a narrow band around the 100 strike for the entire session, never travelling far in either direction — the signature of hedging flow around a heavily traded strike on expiry day.
2. With the underlying at roughly 100.2, intrinsic is 0.2 and time value is 0.25. More than half of what you would pay is scheduled to vanish within hours.
3. No — and that is the answer. Settlement uses the weighted average of the last half hour, not the closing print. On a chart oscillating between 99.8 and 100.6 all session, that average could land either side of 100. Anyone whose outcome depends on which way it falls is holding a coin flip they cannot observe, which is precisely the position worth not being in.
Terms used
- Cash settled
- Closed out in money rather than by delivery. Index options in India.
- Physical settlement
- Actual delivery of shares. Indian stock options.
- Settlement price
- The weighted average of the final half hour, not the last trade.
- Pinning
- Price clustering near a heavily traded strike on expiry day.
- STT
- Securities Transaction Tax. Charged differently on a sold option than on one allowed to expire in the money.