Hi do you know any exchange that allows leverage for btc trading just like forex leverages of 400:1 800:1?
i think you can try with bitmex.com but i don't have many experience in that site since i am afraid to trading with leverage and i think it will need big budget to trade with leverage. if you want to try in that site, i suggest to be careful and you need to know where the coins will move and only use budget that you want to trade.
BitMEX allows leverage on Bitcoin up to 100x, but no higher than that. I don't know of any exchanges that allow leverages on Bitcoin as high as 400:1 or 800:1. There probably aren't any because Bitcoin's too volatile.