The first interview was a standard phone interview from an HR rep. Pretty basic "tell me about yourself and why you're interested in the company" stuff, just to make sure you're capable of basic human interaction. The second interview was also a phone interview but it was a case interview with a manager in the company. For the third round, they flew me out to the office location I was interviewing for. There were about 5 other candidates, and it started with a presentation about the company. Then we split up and each did 3 one on one case interviews with people in the company ranging from manager to senior executive. We flew home on the same day. I recommend studying up on business cases as the whole point of their interview process is to determine whether you can think critically and present logical, strategic solutions to the case they present you with. Don't be afraid to take your time, use a structured approach and bring graph paper in case you want to draw them some kind of visual.