Jane Street Interview Questions
& Process

The interview process started with a virtual first round that included a case study and a stats problem. Then, there was an in-person final round with two interviews. One interview was a case study, and the other was based on readings about a specific business event. Some candidates had additional interviews after lunch.

I had an online assessment with Jane Street. It was supposed to be a 1-hour interview but felt like it ended as soon as the interviewer joined. They were a bit late and seemed unprepared and uninterested. After some initial technical difficulties, we started. I suggested we introduce ourselves, but the interviewer declined. We immediately moved to the question, which was surprisingly a LeetCode easy. The interviewer emphasized the importance of correctness. I proposed a solution using a less common functional programming approach instead of the typical imperative method. The interviewer initially struggled to understand my solution and criticized it subjectively, despite not fully grasping it. I explained it using functional programming concepts and mentioned its common use in languages like Haskell. However, the interviewer seemed to dismiss this. I also presented other functional and non-functional ways to solve the problem and their relationships. For a collaborative interview, understanding each other's backgrounds is crucial for effective communication. After my explanation, the interviewer accepted the approach and ended the session prematurely, even though we were only halfway through the scheduled time. I asked if we could discuss the solution at a high level, including trade-offs, but the interviewer declined. I had a chance to ask a few questions, but the interviewer appeared disinterested and dismissive. This interview felt like a complete waste of time.

So, first there were three phone interviews, and then a final round. The first one was on basic probability, like Bayes' Rule and Conditional Expectation. The second one was more applied probability problems, using the same ideas but with different setups. The third one had even trickier probability problems, still on those same core ideas. The third round was way harder than the first two.

The interview process involved 3 phone interviews and then final onsite interviews at the London office. The first two phone interviews were straightforward, focusing on probability and puzzle questions. The third phone interview was more open-ended, involving game theory and strategy where I played a game with the interviewer. The final onsite interviews consisted of multiple rounds, including coding challenges, game playing scenarios, market making discussions, and strategy-related questions.