I interviewed in their Jersey City office, the HQ. The interview consisted of 2 stages:
#1 was to meet with the actual team, about 5 people, who were asking questions about operations, about what I did in the past. No trick questions, you should be able to talk about these things freely if you have experience.
#2 interview was a week later to meet with HR and 2 senior managers (including head of electronic trading). The interview seemed out of place because I wouldn't imagine why senior people in such a big company need to waste time on interviewing every single candidate. That's why the interview was dragging, it was hard to keep conversation on professional level.