I trade short credit spreads, ie, vertical call and put spreads, on equities only and currently use optionsXpress. I have a large holding of corporate bonds that I use to cover the option margin requirements. However, optionsXpress only counts 50% of the bonds value towards the option margin requirements. Am I reading the IB website correctly (http://www.interactivebrokers.com/en/trading/marginRequirements/bondsMargin.php?ib_entity=llc) in that they only require 10% maintenance margin for investment grade bonds and 20% for any listed bonds, which means they count at least 80% of the bonds value towards other margin requirements? Thanks, Paul H.