Its called a holding rate - I think its distinct from margin rate. CMC Markets changed it from about 5% to 250% on the commodity overnight, while I was in the position. Effectively, this means I will probably have to close my position at a big loss because I cannot remain in the position with those holding costs, its like $500/day. I had no idea they could pull such a move on you - in my opinion it makes me think investing with a CFD provider is extremely dangerous. I was OK with the risk exposure, but I didn't understand that the CFD provider can decide to destroy your holding, at any point.
Maybe its just CMC Markets, not sure if other CFD providers skewer their clients like that. I think that's how they make money.
