383655dd_s_Relating_to_Security_Futures__Description_of_Offset
[0] 13 Individual stock or narrow-based security index [Initial Margin Requirement] The initial margin required under Regulation T for the long stock or stocks. 5% of the current market value, as defined in Regulation T, of the long stock or stocks. [Description of Offset] 
Short security future and long position in the same security (or securities basket) underlying the security future
Final Rule: Customer Margin Rules Relating to Security Futures