sbusso 

Optionally, what broker would you recommend for non US resident ?

As a non US resident I've been working with NTB and Dorman and I've found both great regrding customer support and charges. NTB offers decreased intraday margin as well.

thanks, i will have a look. That is the second time I hear about them this week and the first time was from a story of someone who got the wrong credentials from them and ended trading with someone else money.