Went through 5 rounds of interview including HR Screening, Technical, Business Case, Senior Manager, and Partner. The process took a little while (5 weeks) but the HR specialist on my case kept me posted. Each round was very different and not necessarily harder from the previous one. IMO, they are looking for people who stick with their gut and don't easily sway. The decision finally comes down to the Partner who discusses with the Sr. Manager before making the call. IME, all my interviewers encouraged me throughout the process. There were times when they raised an eyebrow after my response and expected me to change my mind-- this is a test. If you can justify your opinion with concrete data and models, you are fit. In terms of technical requirements, they expect you to have some foundational knowledge of concepts. I couldn't answer two questions in my technical round but instead of giving a BS answer, I expressed my gap in knowledge but followed it with a will and curiosity to learn.