Met them first at a campus career event and they caught my interest. The first interview was over the phone because I was unable to do it on campus during the event. Then invited me to an onsite interview in their Chicago office. They put me up in a nice hotel and, for those that it matters to, got my reimbursed for the trip really quickly. The interview process took around 4 hours, had 4 separate interviews, 2 interviewers per interview. One was a code architecture exam, a coding question where they put you at a computer and give you a problem, one behavioral, and one general problem solving interview. They also had lunch and a brief of tour of their trading areas. They got back to before the end of the week with the outcome of the interview. At just about every stage I felt they acted professionally.