Expiry is a calendar filter, not a personality
Days-to-expiry belongs in a column. Also: the Indian expiry calendar changed, and your history spans both versions.
For a lot of Indian retail books, the entire year happens on two or three days-to-expiry buckets. That is worth knowing about yourself, in the same way it is worth knowing which hand you write with.
Add a days-to-expiry column
Zero, one, two, rest of week, next series. Group P&L by that and the shape of your trading appears immediately — usually more concentrated than you would guess.
Nearly four fifths of the year sat inside two days. Illustrative journal data, not a live book and not a performance claim.
Your history spans two expiry calendars
From 1 September 2025, NSE index and stock derivatives moved to Tuesday expiries while BSE moved to Thursday, after SEBI restricted expiries to those two weekdays. Contracts expiring on or before 31 August 2025 kept the old schedule.
So any "P&L by weekday" chart that crosses that date is comparing two different calendars. Split the series or annotate it.
| Exchange | Contract | Old expiry day | Current expiry day |
|---|---|---|---|
| NSE | Nifty weekly | Thursday | Tuesday |
| NSE | Monthly index and stock | Last Thursday | Last Tuesday |
| BSE | Sensex weekly | Tuesday | Thursday |
| BSE | Monthly | Last Tuesday | Last Thursday |
Write what happened, not what the timeline said
Expiry-day notes fill up with borrowed opinions about pin levels and closing auctions. Keep your own: where you were positioned, what filled, what you did in the last thirty minutes.
Key takeaways
- Store days-to-expiry on every derivatives fill.
- Annotate the September 2025 expiry-day switch in weekday charts.
- Keep expiry commentary personal and factual.
Where these numbers come from
- Economic Times — NSE expiry moves to Tuesday, BSE to Thursday
- ICICI Direct — revised expiry day tables
Not advice, not a call. NiyataBook is a personal trading journal, not a SEBI-registered investment adviser or research analyst. Everything above looks backwards at trades that already closed. What happened in a book does not promise what happens next, and F&O can take a year’s savings in a week.