Module 7 Recap — Expiry Day Mechanics
The current expiry calendar, how each contract settles, the forces that move expiry day, and how to trade it — in one place.
This module rebuilt expiry trading for the post-2024 regime, where SEBI's rules left one weekly index expiry per exchange and moved the days. This recap pulls the calendar, the settlement rules, the expiry-day forces and the strategy playbook into a single reference.
If anything here surprises you, it's probably because you learned the old calendar — re-read the schedule chapter first.
The calendar
NSE NIFTY: weekly Tuesday, monthly last Tuesday. BSE SENSEX: weekly Thursday, monthly last Thursday.
BANK NIFTY, FINNIFTY, MIDCPNIFTY: monthly only (weeklies discontinued Nov 2024), last Tuesday. Single stocks: monthly only, physically settled.
Holiday on an expiry day shifts expiry to the previous trading session.
Settlement and the Greeks
Index = cash-settled to a last-half-hour average; single stocks = physically settled (real share delivery — the big retail trap on ITM stock options).
Expiry compresses the Greeks: theta and IV crush deflate premium (buyers can be right and still lose); gamma spikes at-the-money, making moves fast and pinning/breaking both possible.
How to trade it
Harvest decay with defined-risk spreads, not naked options. Pin trades target max-pain/dominant-OI but are short gamma — cap the risk. The recurring blow-ups are naked selling (fat tail) and lottery buying (negative EV). Size for the gamma-accelerated worst case.
Above all: know which contract you're in and which day its clock runs out. The most common post-2025 error is trading NIFTY as if it still expires Thursday, or hunting for a BANK NIFTY weekly that no longer exists.
Common misreads
- Carrying the old calendar in your head (Thursday NIFTY, BANK NIFTY weeklies) — both are gone.
- Forgetting single-stock physical settlement and walking into a delivery obligation.
- Trading expiry without defined risk in a gamma-charged session.
Key takeaways
- NIFTY Tue / SENSEX Thu weeklies; NIFTY & BANK NIFTY monthly last Tue, SENSEX last Thu.
- BANK NIFTY/FINNIFTY/MIDCPNIFTY are monthly-only since Nov 2024.
- Index cash-settled; single stocks physically settled (delivery risk on ITM).
- Expiry Greeks: theta + IV crush deflate premium; gamma accelerates moves.
- Trade defined-risk; the blow-ups are naked selling and lottery buying.
Expiry mechanics in summary
If I remember only one thing from this module, what should it be?
Know which contract you're trading and which day it expires under the current rules — NIFTY Tuesday, SENSEX Thursday, BANK NIFTY monthly (last Tuesday) — and never hold an in-the-money single-stock option to expiry unless you intend to take delivery. Those two facts prevent the most expensive expiry mistakes.
What's the single biggest change from the old expiry regime?
There's now one weekly index expiry per exchange (NIFTY on NSE, SENSEX on BSE), and they're on different days. BANK NIFTY, FINNIFTY and MIDCPNIFTY lost their weekly options entirely and trade monthly-only. If your knowledge predates late 2024, the calendar you learned is obsolete.
Why are index and stock settlements different?
Index options are cash-settled because you can't deliver an index. Single-stock derivatives are physically settled — real shares change hands — which SEBI mandated to keep stock-derivative prices tethered to the underlying cash market. The practical consequence is delivery risk on any in-the-money stock position held to expiry.
What's the safest expiry-day approach for a newer trader?
If you trade expiry at all, use defined-risk structures (spreads) sized for the worst case, and avoid both naked selling and far-OTM lottery buying. But there's no obligation to trade expiry — many traders simply stand aside on the most gamma-charged session and trade the days around it instead.
Where does this connect in Strota Learn?
It builds on Module 1 (F&O mechanics, settlement, rollover), Module 3 (the option chain, max pain, OI strikes) and Module 4 (the Greeks). Use the live NIFTY option chain to watch max pain, PCR and the dominant OI strikes that drive expiry-day pinning in real time.