Applied online through their site and was very quickly booked in for a technical phone interview the next week. The interview itself was moderately difficult, but was made worse by taking place over arguably the world's worst phoneline with an interviewer with relatively poor English skills (leading to a lot of confusion with regards to word meanings etc.) and an incredibly heavy accent. The questions themselves were relatively challenging but were made more difficult by the interviewer providing wrong information when asked for clarification, which he would then backtrack on a short while later (this happened multiple times). It honestly seemed a very amateur operation and I'd expect much better from a company as large as BNP Paribas.

Applied through their official website. A recruiter contacted me and scheduled the interview. To my surprise, the interviewer turned out to be the Head of the department I had applied to. Unfortunately, I didn't perform well and felt like I came across as unprepared. At the end of the interview, I asked a simple question: "What's the most difficult or interesting problem you've worked on at BNP?" His response was, "I don't think any of the problems are big or tough for me." After saying that, he abruptly ended the call.