Option expiry mechanics.

Expiry day is when option positioning collapses into reality. Every contract that's still open at the cut-off settles. Understanding the schedules, the settlement rules, and the last-hour dynamics is the difference between trading expiry deliberately and being its passenger.

Indian index expiry schedule

Settlement mechanics

Indian index options are cash-settled in INR. No physical delivery of underlying baskets. On expiry day, settlement is based on the final settlement price (FSP) calculated by the exchange.

The FSP is the volume-weighted average price (VWAP) of the index over a designated window — typically the last half hour of trading on expiry day. This is to prevent last-second manipulation of the closing print.

Once the FSP is calculated, all open contracts settle. ITM options receive their intrinsic value in cash; OTM options expire worthless. The margin held against your position is released or applied accordingly.

The last hour of expiry day

The behavior of an index in the final 30–60 minutes of expiry day is structurally different from any other trading session. Two effects dominate:

1. Gamma collapse

As expiry approaches, the gamma of ATM options spikes. Small spot moves cause large delta changes, forcing hedgers (market makers, writers) to rebalance in or against the move. This produces sharp, self-reinforcing intraday swings — especially when spot is hovering near a heavy OI strike.

2. Pin risk

Spot prices often "pin" near strikes where heavy OI is concentrated. The combined hedging activity of writers anchored to that strike creates a magnet effect. Max Pain captures the aggregate version of this; individual heavy strikes can pin even when overall Max Pain is elsewhere.

Reading expiry day positioning

By Tuesday for SENSEX or Thursday for NIFTY, most of the positioning is already in place. What changes in the final session is concentration — OTM contracts decay rapidly, ITM contracts behave like the underlying.

Useful expiry-day reads:

• Spot vs Max Pain gap shrinking through the session typically signals successful "pinning."
• Spot pulling away from Max Pain in the last hour usually means a breakout has overpowered writer defense — often news-driven.
• Heavy short covering in the final 30 minutes on the call side suggests writers are giving up resistance, anticipating a higher close.
• Heavy short buildup in the final 30 minutes on call strikes well OTM = writers selling fresh contracts for the next expiry's premium, treating today as done.

Rolling forward

Traders who want to keep a position past expiry "roll" it — close the near-expiry contract and open the equivalent position in the next expiry. Most rolling activity in Indian indices happens on the Wednesday before NIFTY Thursday expiry, or Monday before SENSEX Tuesday expiry. The volume profile shifts visibly to the next-week chain on those days.

On RetailInterest you can see next-week chain data for NIFTY and SENSEX alongside the current week, making rolling decisions easier.

BTC options expiry — Deribit and Binance

BTC options run 24/7 — no market open/close. Expiry happens at a fixed UTC time regardless of weekday for daily options. Settlement value on Deribit uses an index price averaged over a window before expiry. Settlement on Binance follows their index methodology.

Holiday adjustments

When an Indian expiry day falls on a market holiday, expiry is moved to the previous trading day. NSE and BSE publish the calendar; the RetailInterest terminal reflects the adjusted expiry automatically in the chain header.

Major examples to watch: Holi, Independence Day, Diwali Muhurat Trading sessions, Budget Day (occasionally), Republic Day. Plan expiry-week trades around the published calendar — don't assume.

Margin and exercise mechanics

Indian index option writers post SPAN+Exposure margin maintained by the clearing corporation (NSE Clearing, ICCL for BSE). Margin is revised intraday based on price movement and volatility — be aware that a sudden move can trigger an intraday margin call.

Buyers pay full premium upfront. There is no margin obligation for buyers, but the entire premium can decay to zero on expiry day if the option is OTM.

On expiry day, ITM options are auto-exercised by the exchange. There's no "exercise vs hold" decision to make at the terminal — settlement is automatic.

The "do not roll" trap

Letting positions expire ITM can incur exchange settlement fees that exceed the intrinsic value on small lots — especially for stock options (less of an issue for index options, which are cash-settled cleanly). Always check the broker's contract note after expiry to confirm settlement was clean.

Common expiry mistakes

• Holding deep OTM weeklies overnight. Theta decay is non-linear; the final 24 hours often wipes out remaining premium.
• Adding fresh longs in the last hour. Gamma is too high — small moves produce outsized losses on the wrong side.
• Ignoring holiday adjustments. Treating "Thursday" as always being expiry day. Check the calendar.
• Rolling at illiquid times. Best rolling liquidity is mid-day on the day before expiry, not the last 30 minutes.

How RetailInterest displays expiry data

Each chain header shows the active expiry date and label. For NIFTY and SENSEX, you can switch between weekly, next-week, and monthly chains. For monthly-only indices (BANKNIFTY, FINNIFTY, MIDCPNIFTY, BANKEX) the monthly chain is the only view. BTC chains show daily and weekly expiries side-by-side.

Holiday adjustments are reflected automatically — the chain header shows the actual settlement date, not the nominal weekday.

FAQ

When does NIFTY weekly expire?

Thursday of each week, 15:30 IST. Moves to the previous trading day if Thursday is a holiday.

When does SENSEX weekly expire?

Tuesday of each week, 15:30 IST. Holiday rule same as NIFTY.

Do BANKNIFTY weekly options exist?

No longer. SEBI's 2024 rationalization restricted weekly contracts to one per exchange. BANKNIFTY is monthly-only on NSE now.

Are Indian index options cash-settled?

Yes — all NIFTY, BANKNIFTY, SENSEX and other Indian index options settle in INR. No physical delivery.

What time do BTC options expire on Deribit?

08:00 UTC. Daily, weekly (Fridays), and monthly (last Friday) — all settle at the same UTC time.

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