I think CFD's work differently from Spreadbetting. You tend to need a lot more money to trade these and according to IG the average bet/trade is £10,000 - £20,000. That on a 5% margin is £200,000 to £400,000 worth of shares. Which for someone like vodaphone would buy you more the £1,000 a point. Never traded these, so I could be completely wrong. Best bet is just to phone them up and ask them. Not sure how it works with indices.