Quant interview preparation

Prop market making and quantitative research, weighted the way the interviews actually are: probability and expected value, statistics and machine learning, market making logic, programming and options. Every question is either traced to a named firm from a public candidate report, or tagged at desk level when we could not trace it, and every probability answer shows the reasoning path rather than just the number.

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Question bank

100 questions, mapped to the firms that asked them

Questions
100
Traced to a firm
53
Firms
15
Updated
September 2026
Asked at
All firmsOld Mission Capital12Tower Research Capital10Jump Trading7Akuna Capital5Citadel4D.E. Shaw3Jane Street3AQR Capital Management2DRW2Millennium Management2Schonfeld2Squarepoint Capital2Susquehanna International Group2Belvedere Trading1Optiver1
Topic
All topicsProbability10Coins, cards and games6Expected value8Statistics11Market making15Estimation and mental maths4Stochastic processes4Regression5Machine learning6Time series6Programming10Options and derivatives8Fit and motivation7
Level
AnyCoreIntermediateHard
Type
AnyBrainteaserTechnicalCaseMarket viewFit
Showing 1–1 of 1 · filtered from 100Clear filters
  1. 100You are working through a problem and you cannot finish it. How do you handle that in an interview?Fit and motivationIntermediateevery roundJane StreetEngineering · New York · 2026

    Say this

    Keep talking, and make the thinking visible. How you got there matters more than whether you got there. State what you know, name the structure you are looking for, say what you have ruled out and why, and put a bound on the answer even when you cannot compute it exactly.

    Then walk it

    1. Narrate the state of your reasoning, not just your conclusions. This is what I think the answer depends on, here is the approach I tried, here is why it failed, here is what I would try next. That is a gradeable answer even without a number.
    2. Give a bound or an approximation. The answer is between a half and two thirds, and here is the argument for each side, is worth far more than silence. Traders live on bounds.
    3. Simplify deliberately and say that you are doing it. Do the two-dice version, or the n equals 2 case, or the discrete version of the continuous problem, then say I would extend this by induction. Interviewers will usually let you.
    4. Ask for the hint properly. Not I am stuck, but I think the sticking point is whether these events are independent. Am I right that they are not? That is a precise question and it shows you know where the difficulty lives.
    5. And do not bluff, ever. A confident wrong assertion is far worse than an honest I do not know this result, but here is how I would derive it. On a trading desk, someone who hides uncertainty is dangerous, so the willingness to say I am not sure, with a reason, is itself part of what is being assessed.

    Where candidates lose it

    Going silent while you think, or worse, asserting something you do not believe to fill the gap. Silence gives the interviewer nothing to grade, and bluffing fails the honesty test that every trading firm runs. Narrate, bound the answer, simplify the problem, and ask a precise question when you need one.

    Expect next

    • Tell me about a time you were confidently wrong.
    • How do you decide when to abandon an approach?
    • What would you do if a senior trader gave you a number you thought was wrong?

    Reported by candidates at Jane Street (Engineering, New York, 2026). Source: Wall Street Oasis.

Firm tags come from public, anonymous candidate reports on Wall Street Oasis: strong signal, not sworn testimony. Firms are named as the places a question was reported, not as partners of Fin Maverick. Answers are written for this page to show how to think out loud; they are not scripts to recite.