There is a CodeSignal that they send out that you have 2 weeks to complete. Still waiting on hearing back results of that but the hiring manager contacts you personally.
Got an Online Assessment from them which was in code signal 2 weeks after I applied. 4 questions in 100 minutes where the questions varied from easy to hard in that order.
I applied online. I interviewed at Hudson River Trading
Interview
Got to coding interview process and was able to answer 2/4 of the questions. I don't remember most of the questions though. Interviewer that sent out the email seemed nice.