1) For short equity options, the margin requirement is 20% of the underlying stock value plus the premium received, minus any out-of-the-money amount, with a minimum of 10% of the underlying value. 2) For call and put spreads, the margin requirement can be reduced or eliminated depending on the expiration and exercise prices of the long and short options. 3) For short straddles, the margin requirement is the greater of the two leg requirements plus the other leg's premium. 4) For foreign equity and index options, the margin requirement is generally 100% of the premium plus a percentage of the underlying value, minus any out-of-the-money amount or premium received.