A corporate action which affects the securities without giving any choice to the security holder.

Initial margin is collateral placed by one party with a counterparty or clearing house at the time of a deal, against the possibility that the market price will move against the first party, thereby leaving the counterparty with a credit risk. Variation margin is a payment made, or collateral transferred, from one party to the other because the market price of the transaction or of collateral has changed. Variation margin payment is either in effect a settlement of ...