Yes, I would assume so.
However; they hired a team of F# programmers a few years back, and it is their main modeling language now.
It's because of institutions like CS that F# moved beyond the research level at Microsoft...
Yes, it's quite surprising. It's not unknown in the industry, though. CS does all (?) of their modeling in it.
It's very well suited for trading, and a joy to program in. It lends itself nicely to concurrent programming.