Haskell has much more of a group inside of a company will use it as their primary environment then adopting it wholesale. Haskell is used extensively in trading with almost every major bank and hedge fund using it, although no one talks about it. It is also extensively used in energy companies.
There are a few companies out there that use it as their primary language such as Tsuru Capital and my company, Alpha Heavy Industries. By definition companies using it as their primary language will be smaller companies. Standard Chartered has a very large Haskell group.
That Haskell is used extensively in trading is quite interesting to know. This distinction did not come out that well on the wiki link. This is probably the reorganization that the page needs. Split in to sections highlighting companies which use Haskell as primary language, then split along industry lines.
Highlighting companies which use Haskell as primary language will be beneficial to both the language and the companies. Brings along a trust factor that real money can be made while using on Haskell.