— GUIDE —
QUANT TRADER INTERVIEW PREP
The trader track from application to final round: what each stage is actually measuring, how to train for it, and where candidates spend time that does not pay.
UPDATED 2026-10-08 · 6 MIN READ · BY THE VARIANCE TEAM
Most preparation fails by treating five different filters as one exam. Each stage of a trader process rewards a different habit, so it helps to know which one you are training.
The trader track, stage by stage
Details vary by firm, but the shape is consistent enough to plan against. Each stage filters on something different, which is why preparing for "the quant interview" as one thing tends to go badly.
| Stage | What it measures | Where to train |
|---|---|---|
| Online assessment | Speed and accuracy under a clock, with scoring rules defined in the invitation | OA prep guide |
| Math and probability round | Whether the methods are actually retrievable when someone is watching | Probability questions |
| Market-making round | Pricing, quoting, and updating on information | Market-making guide |
| Estimation and reasoning | Whether you can commit to a number with incomplete information | Estimation guide |
| Final and behavioral | How you handle being wrong, and whether people want you on the desk | Practice out loud with a person |
A four-week plan that fits around a job or a degree
- Week 1, arithmetic base. Twenty minutes a day of timed mental math. The goal is not to be a calculator; it is to stop spending working memory on multiplication so it is free for the actual question.
- Week 2, probability and expected value. Work questions rather than reading theory. Track which ones you knew but could not retrieve fast enough, because that gap is the thing being tested.
- Week 3, market making and estimation. Start saying answers out loud, with a bid and an offer, every time. Record yourself once; it is unpleasant and effective.
- Week 4, full mock rounds. Mixed questions, timed, with someone allowed to interrupt and push back. Interruption is the part you cannot simulate alone.
The habits interviewers actually reward
- Narrate before you compute. State your read of the problem and the approach you are picking. Explain the method so the interviewer can follow and correct your reasoning.
- Quote two sides. When asked to make a market, give a bid and an offer. If asked only for expected payoff, compute that first.
- Update out loud. If new information arrives, say what it changed and why. This is the closest thing to watching you trade.
- Ask before assuming. Clarifying the payoff is not a stall, it is the first step of the answer.
- Be specific about uncertainty. "Roughly 60, and I would widen because I am unsure about the tail" is a stronger answer than a confident 60.
What not to spend time on
For Jane Street quantitative trading, the firm says finance knowledge is not tested. Other employers and experienced roles can require it; follow their published role requirements. Hunting for leaked question banks is worse than wasted, since the questions rotate and the habit trains recall instead of reasoning.
Firm-specific reading has a place, but late and briefly. Start with what the firm publishes itself, as in the Jane Street and Citadel Securities guides, and treat everything else as a rumour with a date on it. For how firm types differ in what they weight, see what quant firms test.
Adapt the plan to your role
This schedule is for trading preparation. Research applicants should add statistics, coding and discussion of a project; developer applicants should prioritize programming and systems work. The firm can omit, combine or reorder the stages shown above. Jane Street’s role-specific interview guidance, checked 8 October 2026, illustrates those differences. Your recruiter and current job description determine the actual process.