Futures options, as well as futures margins, are governed by the exchange through a calculation algorithm known as SPAN margining. For information on SPAN and how it works, please research the exchange web site for the CME Group, www.cmegroup.com. From their web site you can run a search for SPAN, which will take you to a wealth of information on the subject and how it works. The Standard Portfolio Analysis of Risk system is a highly sophisticated methodology that calculates performance bond requirements by analyzing the “what-ifs” of virtually any market scenario.
In general, this is how SPAN works:
SPAN evaluates overall portfolio risk by calculating the worst possible loss that a portfolio of derivative and physical instruments might reasonably incur over a specified time period (typically one trading day.) This is done by computing the gains and losses that the portfolio would incur under different market conditions. At the core of the methodology is the SPAN risk array, a set of numeric values that indicate how a particular contract will gain or lose value under various conditions. Each condition is called a risk scenario. The numeric value for each risk scenario represents the gain or loss that that particular contract will experience for a particular combination of price (or underlying price) change, volatility change, and decrease in time to expiration.
The SPAN margin files are sent to IB at specific intervals throughout the day by the exchange, and are plugged into a SPAN margin calculator. All futures options will continue to be calculated as having risk until they are expired out of the account, or are closed. The fact that they might be out-of-the-money does not matter. All scenarios must take into account what could happen in extreme market volatility, and as such the margin impact of these futures options will be considered until the option position ceases to exist. The SPAN margin requirements are compared against IB's pre-defined extreme market move scenarios and the greater of the two are utilized as margin requirement.