I am told That Currenx allows you to sell the base currency at the offer rate?! Example Euro/$ bid/offer 1.2392/1.2400. when you sell euro you sell at 1.2400?
You can do it with most platforms, not just Currenex. Just use a limit order. Currenex may offer slightly better chance for such an order being filled.
If this is the case........and since the offer rate is always higher then sell the base currency and immediately buy it back at the bid rate, you will profit the spread. of course you can do it on all platforms but you will never get filled. It amazed because that is the way the platform is set. you hit the offer rate to sell. I have been dealing with Saxobank and the opposite is true.