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
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Type
AnyBrainteaserTechnicalCaseMarket viewFit
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  1. 098How would you describe the internet to someone who has just time travelled from thirty years ago?Fit and motivationIntermediatetechnicalCitadelQuantitative Trading · Sydney · 2025

    Say this

    Anchor it in something they already have, then build outward. Thirty years ago they had a telephone network and a public library, so I would say: imagine the phone system, but instead of connecting two people it connects every machine, and instead of voices it carries copies of anything written down.

    Then walk it

    1. Start from their reference frame. Someone from the mid-nineties knows telephones, fax machines, libraries, post and television. Every explanation should be a modification of one of those, not a new concept from scratch.
    2. Then the one structural idea that makes everything else follow: the cost of copying and sending information fell to approximately zero, and nobody owns the middle of the network. From that single fact you can derive email, search, shopping, streaming and social media without explaining any of them separately.
    3. Give one concrete, checkable example. The entire contents of that library, searchable in a quarter of a second from a device in your pocket, and it is free because someone sells advertising next to the answer.
    4. Then say what they would find strangest, because that is the interesting part of the answer. Not the technology but the consequences: that attention became the scarce resource, that distance stopped mattering for information but not for goods, and that privacy became something you trade rather than something you have.
    5. Check understanding rather than lecturing. I would ask them what they want to do with it and explain that, because the tailored answer lands and the general one does not. This question is a communication test, so the move that scores is structure plus adapting to the listener, not encyclopaedic completeness.

    Where candidates lose it

    Diving into TCP/IP, packets and DNS. The question tests whether you can teach, not whether you know how it works. Anchor in their existing mental model, lead with one organising idea, and use a concrete example. Rambling without structure is the common failure, so state your three-part plan before you start.

    Expect next

    • Now explain machine learning to the same person.
    • What would they find most surprising about the consequences?
    • Do it in thirty seconds instead.

    Reported by candidates at Citadel (Quantitative Trading, Sydney, 2025). 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.