The on-site interview was definitely one of the hardest interviews I had for finding a quant researcher position. The overall interaction with the company was pleasant and two of the three interviews were also very enjoyable with the interviewers clearly knowing their stuff. However, the third interviewer seemed to be absent, was unfamiliar with basic statistics expressions and generally made a weak impression. Curiously, I got the worst feedback from this third interview (even though the first two ones were probably also not good enough to make it to the next round). Overall, this experience ruined an otherwise pleasant interaction with the company.