one of the biggest steal companies in the world
Do tell. Enron, maybe?
High frequency trading
Most of the code driving that is written in Haskell
That's weird. The very article you link says most of it is written in C/C++, with a bunch of other stuff thrown in here and there. One guy said he used Visual Basic.
It's not a monopoly. It's just no one wants to learn reverse polish notation to use an HP calculator.
More the fool, they.