It is a long process to go through, but if you get an offer in the end, it is mostly not only for an internship but for a full time position afterwards, as the company rarely hires people from outside for higher positions. I did an online assessment test, afterwards a reasoning test at university and finally I got invited to spend one day in Geneva where I had to go through 3 interviews. On the whole, the people were very friendly, and you get even paid flights and hotel stays to come to the event. Most questions in the interview are behavioral and you have to answer by STAR technique. I also had to solve a small brain teaser/math question, which was not really difficult, they just want to see how you react and work.