[adamdusty]

This[0] guy claims to work at a shop that uses C# for HFT. This[1] comment chain from a post about Java HFT has users claiming to use C# for HFT.

[0]: https://www.youtube.com/watch?v=ug_UC4lxMr8 [1]: https://news.ycombinator.com/item?id=24896616