It's to do with the products your looking to trade. A private client has certain rights and protectionsas he's deemed to be insufficaintly experienced to understand the risks in trading more sophisticated products. All private client funds have to be held in segregated accounts. By siging the intermediate customer agreement, you're vouching that you have sufficient trading knowledge to understand the risks involved in trading riskier products. Presumably this is to open a CFD trading account. Because intermediate clients understand the risks, the FSA doesn't insist that all their funds are kept segregated - the can be held in a non-segregated account. You do lose some protection, but you can't open a CFD account without opting up. Oddly, you can still spread bet. The ombudsman service is only designed to protect private clients, not expert investors.