Jane Street Interview Questions

Updated Sep 14, 2014
Updated Sep 14, 2014
425 Interview Reviews

Interview Experience

Interview Experience

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Candidate Interview Reviews

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  1.  

    Trader Intern Interview

    Anonymous Interview Candidate
    Anonymous Interview Candidate
    Application Details

    I applied through college or university. The process took 2 weeks - interviewed at Jane Street in April 2014.

    Interview Details

    Applied in early April, had first interview a week ago, and second interview yesterday. The interviewer for first round was really nice. Gave me some quick mental math (1,000,000 - 111, 12% of 56, etc), and he then gave me a couple probability questions. Second interview was more difficult - one warm up and then one tough question. Prepare to get wrecked.

    Interview Questions
    • Expected value of heads and tails of two coin flips -> E(t(10-t) = 10E(t) - E(t^2) = 50 - (25 + 10/4) = 22.5

      What is the set of numbers between 2 and 30, without the same common factor (e.g. 26 and 24 share 2, so they cannot be in the same set) that will you give you a max sum?

      Using the same rules, what is the highest possible number you can have in a set of 1000?
        View Answers (8)
    No Offer
    Positive Experience
    Difficult Interview
  2.  

    Quantitative Researcher Interview

    Anonymous Interview Candidate
    Anonymous Interview Candidate
    Interview Details

    Submitted resume online and get a phone interview two weeks later

    Interview Questions
    No Offer
  3.  

    Trading Intern Interview

    Anonymous Interview Candidate
    Anonymous Interview Candidate
    Application Details

    I applied online. The process took 3 weeks - interviewed at Jane Street in February 2014.

    Interview Details

    Applied online. Contacted for interview the day after. Made it to round 2. Interview was quite difficult. Make sure to review probability and statistics for the interview. Don't bother studying behavioral questions. Most annoying thing was how Jane Street stopped replying after round 2, so I assume I didn't make past round 2.

    Interview Questions
    • The interviewer gives you 100 blank cards, and you can write a single positive integer on each card. The interviewer looks at the cards when you're done (so he knows the probability distribution of the deck), then shuffles the deck. The interviewer guesses the top card of the deck, and if he's right, he makes in $ the number written on the card. What numbers should you write on the cards to minimize the expected return of the interviewer?   View Answers (4)
    No Offer
    Positive Experience
    Difficult Interview
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  5.  

    Quantitative Trader Interview

    Anonymous Interview Candidate
    Anonymous Interview Candidate
    Application Details

    I applied online - interviewed at Jane Street.

    Interview Details

    30 minute phone interview. The interviewer asked approx. 9 math questions ( 3 mental math, 3 probability and 3 word problems). I was given approx. 30 seconds per question. Answered at least 7 of them correctly.

    Interview Questions
    • What is the probability of getting a sum of 10 if you roll three dice?   View Answers (3)
    No Offer
  6.  

    Quantitative Trader Interview

    Anonymous Interview Candidate
    Anonymous Interview Candidate
    Application Details

    I applied through college or university - interviewed at Jane Street in November 2013.

    Interview Details

    Had 2 rounds of phone interview. The first round had about 5 questions, 2 on basic arithmetic, 2 on probabilities (standard card problems), and 1 brainteaser. The interviewer, though late for the call, gave a lot of guidance. The 2nd round interviewer was really rude. He was giggling the whole time and hung up abruptly when I got the first probability question wrong.

    No Offer
    Average Interview
  7.  

    Software Development Intern Interview

    Anonymous Interview Candidate
    Anonymous Interview Candidate
    Application Details

    I applied through college or university. The process took 3 weeks - interviewed at Jane Street in January 2014.

    Interview Details

    After submitting an application on my University website, I was contacted a few weeks later to set up a coding interview by phone. The interview focused on linked list implementation, optimization and optimal algorithms for searching, inserting, etc. All employees I interacted with in the process were very kind and knowledgable, seems like a great company!

    Interview Questions
    • Optimizing search for smallest (inner) list within in a list of lists   Answer Question
    No Offer
    Average Interview
  8.  

    Trader Intern Interview

    Anonymous Interview Candidate
    Anonymous Interview Candidate
    Application Details

    I applied online. The process took 4+ weeks - interviewed at Jane Street in March 2014.

    Interview Details

    applied online got an interview the next day. passed the first round waiting for the second round. The interviewer is nice. She did not ask a lot about my background. Lots of mental math and probability questions. The questions are not that tough. no pencils and paper for the first round.

    Interview Questions
    • Basketball player A and B. Game 1 and 2. In both game, A has a higher shooting average than B. Is it possible that B has a higher overall shooting average. Give an example if possible.   View Answers (5)
    No Offer
    Difficult Interview
  9.  

    Assistant Trader Interview

    Anonymous Interview Candidate
    Anonymous Interview Candidate
    Application Details

    I applied online. The process took 2 weeks - interviewed at Jane Street.

    Interview Details

    telephone interviews just brain teasers. Missed a trick on the first interview but they still wanted to schedule a second one so it's mostly about the reasoning.

    Interview Questions
    • person A has a 30 sided and person B has a 20 sided die. both players role and the person with the highest role win (on a draw B wins). the loser pays the winner the value of the winners die.
      1. calculate expected value of this game for player A (easy)
      2. how does this value change if player B can re-roll and when should he re-roll.
      3. now how much is it worth for player A to get a re-roll option in this scenario.
      4. remove player A reroll. how many re-rolls do player B need in order for him to be a favorite in the game.

      i believed i solved 4 and 2 I had a decent idea but 3 is very difficult since optimal strategy might change based on opposing players optimal strategy.
        View Answers (5)
    No Offer
    Difficult Interview
  10.  

    Intern Interview

    Anonymous Interview Candidate
    Anonymous Interview Candidate
    Interview Details

    Applied online and heard back within about a week. Good communication; had to demonstrate excellent knowledge of excel and mathematical skills. I did not receive an offer in the end but would be happy to apply again. Have heard great things.

    Interview Questions
    No Offer
  11.  

    Software Development Engineer Intern Interview

    Anonymous Interview Candidate
    Anonymous Interview Candidate
    Application Details

    The process took 3 days - interviewed at Jane Street in March 2014.

    Interview Details

    The interview process began with a conversation and resume drop at a career fair, but I was told that applying online would have been the same. A couple weeks later, I received and email asking for availabilities in a two-week window.

    The first interview lasted about 1 hour 15 minutes. Interviewer was very friendly, and passionate about his work. It was a phone interview with live coding on code.stypi.com. Questions were straightforward. After a quick intro we went straight into the first question topic, power sets. After question, given an alternate solution involving binary strings. Remaining 30 minutes or so devoted to Q+A. Heard back in 15 minutes (next round)

    Second interview was also a little over 1 hour. Most of the time devoted to a single coding question (it was up to me to break it into parts). Key idea was to break an abstract idea into codable elements, show your thinking process, and make a useable interface. Heard back the following week, no offer.

    Both interviewers were every friendly and did a good job at maintaining a moderate-to-high level of difficulty (occasionally commenting "are you sure?", "um", or "okay" to hint at whether or not I was going in the right direction). First interview was moderate, second quite difficult. Both questions were interesting and unique as far as I could tell.

    Interview Questions
    • Write a function to make a power set (as a list of lists) from a set (as a list). Wrote code in ocaml, although I was told that any language would do.   View Answer
    • Given a 0-9 numerical keypad and three chess pieces (pawn, knight, queen), use any language to write a function such that Input(piece, location)->Output(# of possible phone numbers). Code must compile and run.   View Answer
    No Offer
    Positive Experience
    Difficult Interview

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