Assignment margin

An options trade is margined more than once, because it has more than one financial event to cover. Buying or selling the option itself is one event — that is what initial, exposure and premium margins are for. But when the option is exercised and actually has to be settled, that settlement is a separate event with its own money at stake, and it needs its own margin.

That settlement-stage margin is the assignment margin. The workbook's own words: "Assignment margin is collected for the final settlement obligation of the option. It is levied till the completion of pay-in towards the exercise settlement."

The clearing corporation collects margins from its members to make sure trades settle without default — clients pay trading members, trading members pay clearing members, and clearing members pay the clearing corporation. For options, the margining system largely follows the futures system, with two differences the workbook sets out:

1. Initial margin is levied on the premium value of open option positions, and exposure margin is levied on the notional contract value, computed from the value of the underlying — and exposure margin is collected only on short option positions (sellers), since a buyer's maximum loss is capped at the premium already paid.
2. Two additional margins apply only to options:
   • Premium margin — the premium amount due to be paid to the clearing corporation towards premium settlement, at the client level, levied till the completion of pay-in towards the premium settlement.
   • Assignment margin — collected for the final settlement obligation of the option, levied till the completion of pay-in towards the exercise settlement.

So an option position can attract up to four separate margins over its life: initial and exposure margin while the position is open, premium margin until the premium itself is paid in, and assignment margin once the option is exercised or assigned, until that settlement obligation is paid in. All margins are payable in advance by clearing members, and clearing members report margins due and collected to the clearing corporation daily. Not meeting a margin call attracts penalties, including suspension of the trading facility, disciplinary action, or closing out open positions.

Mr Aakash Verma, trading through a clearing member, holds a long call option position that finishes in the money on expiry and is exercised.

The assignment margin exists precisely because exercise creates a fresh obligation — the difference between the strike and the settlement price now has to actually move — separate from, and in addition to, whatever Aakash had already paid to hold the position open. Once his exercise settlement pay-in is complete, the assignment margin on that position is released; it was never meant to be held indefinitely, only until that specific obligation is discharged.

Chapter 6 (Derivative Markets), section 6.6.2 (Margins), sets out the margining system for futures and then lists premium margin and assignment margin as the two margins specific to options, immediately after explaining that exposure margin on options applies only to sellers. Expect a question naming the margin type from its description — "collected for the final settlement obligation of an option" points to assignment margin, not premium margin — and a question distinguishing when each of the four margins is released.

• Assignment margin is for the exercise/settlement obligation; premium margin is for the premium obligation. The workbook gives each its own, differently worded, sentence — do not swap them.
• Assignment margin is specific to options. Futures are margined with only initial and exposure margin; premium and assignment margins do not arise because a futures contract has no premium and no exercise event.
• Exposure margin on options is charged only to sellers (short positions), not to buyers — a buyer's downside is already capped at the premium paid.
• "Levied till completion of pay-in" means it is released once that specific settlement is paid in — it is not a margin that sits on the position for its whole life the way initial margin does.
• Do not confuse assignment margin with position limits, a separate risk control in the same section that caps the size of open positions rather than margining a settlement obligation.