Two expiry-week hazards

1. Pin risk — when underlying closes very close to a strike price at expiry. Small moves have outsized impact on your P&L.

2. Assignment risk — being forced to fulfill your short option’s obligation (deliver stock or buy at the strike).

Both are amplified on the last day of expiry.

What “pinning” means

An option “pins” a strike when the underlying closes right at (or extremely close to) that strike at expiry. For index options this just means uncertain settlement. For stock options with physical delivery, it means uncertain assignment.

Example: You sold a Reliance 3,000 call. Reliance closes at exactly ₹3,000.05 at expiry. The call is technically ITM by ₹0.05 — you’ll be assigned. But it’s essentially a coin flip whether you’re forced to deliver 250 shares (worth ₹7,50,000) at 3,000.

This is pin risk.

Why pinning happens

Large institutional positions concentrate at “round number” strikes. Their hedging activity (buying/selling underlying to adjust delta) tends to push prices back toward strikes as expiry approaches. This is why stocks sometimes seem to “magnetically” close near heavily-traded strikes.

Managing pin risk

Option 1: Close before the final hours

Simplest rule — don’t hold any short options into the last 2 hours of expiry day if the underlying is near your strike. Close and take the outcome.

Option 2: Buy the option back if it’s at-the-money late

If your short call is trading at ₹2 and underlying is at your strike, buy it back for ₹2. Small cost to avoid unpredictable assignment.

Option 3: Roll to next expiry

If you still want the position, roll it out (see Chapter 24). Extends time and moves you away from immediate pin risk.

Assignment risk — Indian specifics

Indian stock options are physically settled. If your short option is ITM at expiry, you’ll be assigned actual shares.

Short call assigned: you must deliver the shares.

Short put assigned: you must buy the shares.

⚠️ Physical delivery week starts Monday

For monthly stock option expiries, brokers typically restrict positions from the Monday of expiry week. Requirements:

  • Additional margin (often 40-100% of full contract value)
  • May force you to close positions if margin isn’t met
  • Some brokers auto-square off ITM positions on the morning of expiry

Managing physical delivery

Best practice: close all stock options by end of Monday (day before expiry) if:

Deliberate acceptance strategies:

1. Covered call assigned as designed

2. Cash-secured put assigned as designed

3. Rolling to avoid delivery

Index options — no physical delivery

Nifty, BankNifty, Finnifty options are cash-settled:

Because of cash settlement, index options are the safe choice for holding into expiry.

The settlement price problem (index options)

Nifty index settlement uses the average of last 30 minutes of index price. This creates a specific type of manipulation risk:

Pin risk in iron condors

If Nifty closes right at your short strike (either side of an iron condor):

If you know Nifty is heading toward your short strike as expiry approaches, close the entire condor rather than gambling on precise settlement.

Assignment on American-style options

Note: All Indian stock and index options are European style — can only be exercised AT expiry, not before. This eliminates early-assignment risk (which is a major issue for American-style options in the US).

Benefits:

Downside: you can’t exercise early to capture a dividend (a US-market technique). Not usually a factor in India due to structure.

Expiry-day checklist for options traders

For every short-option position:

☐ Underlying more than 1% away from short strike? → Usually safe to hold ☐ Underlying within 1% of strike? → Consider closing ☐ Stock option (physical delivery)? → Close by Monday if any doubt ☐ Index option (cash-settled)? → Can hold with less risk ☐ Any known corporate action on the underlying? → Extra caution

For every long-option position:

☐ ITM at close? → Will be exercised automatically (index) or settle physically (stock) ☐ OTM? → Expires worthless, done ☐ ATM (pin candidate)? → Consider closing to lock in current value

The lazy safe rule

Close all positions by 2 PM on expiry day. You lose the last hour of theta, but avoid all pin/assignment/settlement chaos. For most retail traders, this is the right call.

Only hold into settlement if:

Broker-specific policies

Read your broker’s expiry-week policies at least once. They vary in details and can affect you.