Assistant Trader Intern

Jane Street has five rounds of interviews. The first round is generally on-campus (I got the interview by applying via OCR) and consists mostly of quick mental math questions, followed by a few simple questions about probability (cards/dice). The next three interviews are all over the phone, scheduled via email contact with a designated recruiter. They consist of progressively harder math/probability questions, with some "market making"/confidence interval construction questions thrown in. The fifth and final round is on-site, and is markedly different from any of the previous rounds. You are given 100 poker chips to start the day, and through the course of many interviews are asked to place bets (and win or lose chips) on the answers that you give to various questions (often in the form of making markets/confidence intervals). There is randomness in the outcome of these bets, which the company understands, so they look more at your logic/risk management with respect to your answers and how you place bets. Funny enough, the final round does NOT have the most difficult math questions - the ones I received during the last phone interview (fourth round) were harder. So for the first four rounds, I would recommend that prospective interviewees brush up on their math/probability skills. For the final round, slowing down and thinking about how to answer a question and place a bet are key. There are many more of what I would call "trick questions" in the final round which can be navigated if one actually stops to think about what the answer should be rather than the first, intuitive answer that pops into one's mind. My impression is that if you can pass the first four rounds, then the company believes that your math skills are up to snuff. I believe that the final round is more about testing your risk management and decision under uncertainty skills than the quantitative skills that are necessary to get you through rounds 1 - 4.