I received an internal referral from an employee at the company. The first part of the process involved a skype interview with a person from HR and the manager (since I wasn't in the location at the time). An in-person interview followed with the same two persons, followed by an aptitude test (4 different tests - English, Math, Personality, Reasoning, about 3h in total) and a final interview with a Partner. Because the process took place during the summer it was very slow, as most people were on holidays.