Vermav, I have been trading cfds with a few different suppliers of that product, some market makers and others directly into the the market. From my experience if you trade with a market maker you are trading against them. An example would be if an index was trading between say 3990 and 4025 during the day ,a market maker may cap the higher end as the market peaks to say 4020 and hold the lower end higher to say 4005 with a spread of as much as 4 to 13 points which means that it is possible for you to make nothing from what should be a positive trade. If you use a supplier who charges a small commission but can place your orders directly into the market with no spread then you are far better off in my opinion. As for who to use I would suggest that you do an internet search and trial the various free trials on offer,attend their free seminars ,ask lots of questions then make your own choice based on the information you are given.
