Expiry day is the most exciting and the most dangerous day for option traders. Premiums can multiply in minutes, or melt to almost zero in an hour. Many traders treat it like a lottery. The ones who do better have studied how premiums behave on past expiry days.

This guide explains what happens to option premiums on expiry day, the patterns that keep repeating, and how to study them yourself using historical charts.

Why expiry day is different

An option's premium has two parts:

• Intrinsic value: how much the option is in the money.
• Time value: extra premium for the chance that the option moves further in the money before expiry.

On expiry day, there are only a few hours left, so time value shrinks quickly. By the close, an option is worth only its intrinsic value, and every out-of-the-money option expires worthless.

Theta: time decay speeds up

Time decay is not spread evenly across an option's life. It speeds up as expiry approaches, and it is fastest on the last day. An out-of-the-money option can lose most of its remaining premium even if the index barely moves.

Gamma: small moves, big swings

Near expiry, at-the-money options become very sensitive to the index. A move that would change the premium a little on a normal day can double or halve it on expiry day. That is why you see sudden premium spikes in the last hours.

Patterns you'll see on past expiry charts

Open a few expiry days on the historical options chart and you'll start noticing the same shapes again and again:

• Steady decay in OTM options during quiet periods, often in a smooth downward slope.
• Sharp spikes in options near the money when the index makes a quick move.
• Fast collapse after a spike, when the index stops moving and time decay takes over again.
• Last-hour volatility, when premiums can swing widely as positions are closed.

How to study expiry days on OPIFY

1. Open the historical options chart.
2. Choose NIFTY, BANKNIFTY or SENSEX and select a past expiry.
3. Use a 2x2 layout to show four charts: the ATM call, the ATM put, and one OTM call and put.
4. Set the timeframe to 3 or 5 minutes and focus on the expiry day itself.
5. Note how each option behaved in the morning, around midday, and in the last hour.

Questions to ask on every expiry you study

• How much did the OTM options lose by midday if the index stayed in a range?
• How big was the biggest spike, and how long did it last?
• Did premiums react more to the opening move or the afternoon move?
• Where would a stop-loss have been hit, and would it have saved or cost you money?

Use Bar Replay to practise expiry trades

Studying a finished expiry chart is useful, but practising decisions is better. Turn on Bar Replay, start at the open, and step through the day one candle at a time. Decide when you would enter and exit, and record the result. Expiry days move fast, so this is the safest way to get used to the speed.

Lessons most traders learn from expiry charts

• Holding an OTM option and "waiting for the move" is expensive on expiry day.
• Profits on expiry spikes need to be booked quickly. They rarely last.
• Position size should be smaller, because premiums can move against you very fast.
• A strict stop-loss matters more than on any other day.

Frequently asked questions

Can I see charts of old expiries?

Yes. OPIFY has NIFTY and BANKNIFTY option charts from January 2023 and SENSEX from May 2024. Past expiries are available with OPIFY Premium.

Is it better to buy or sell options on expiry day?

Neither is automatically better. Buyers can gain from sharp moves but face fast decay; sellers collect decay but face sudden spikes. Study past expiries to see how each approach would have worked for your style.

Can I download expiry day data?

Yes. You can export the candle data for any instrument, expiry, strike and timeframe as CSV or Excel.

This article is for education only and is not investment advice. Options trading involves risk, and expiry-day trading carries higher risk.