Last updated: 2012-05-08
Required margin = margin rate × quantity × last daily settlement price × multiplier + margin of hedged positions
The margin of hedged positions appears only in the week of a contract expiration (hedged position = long position in one contract series and short position in an other series of the same contract). It increases day by day until reaching the level to cover the remaining contract series.
Required margin = quantity × ((2 × strike price - last closing price of underlying) × margin rate × 1.5 + last closing price of the contract) × multiplier
Required margin = quantity × ((2 × last closing price of underlying - strike price) × margin rate × 1.5 + last closing price of the contract) × multiplier
Where multiplier = number of underlying items per contract