Margin accounts trading and holding only Future contracts may be allowed a lower intraday margin requirement for a Future contract when market conditions allow. However, this lower intraday margin is rescinded when any Future Option contract for the same Future is added to your position. Future products use SPAN margin to calculate margin requirements. SPAN evaluates overall portfolio risk by calculating the worst possible loss that a portfolio of derivative and physical future instruments might reasonably incur over a specified time period (typically one trading day.) Adding a Future Option to a portfolio that was holding only Future contracts will cause the account's margin requirement to be re-evaluated and a new requirement is applied to the position
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