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Jane Street · Quant trader / software engineer · Quant Trader, new grad / intern

Estimation & Problem Solving (spoken)

Fermi/estimation and open reasoning, plus a light data-analysis and general-interests chat

What they actually ask

The question shapes this round uses. Larpy does not read these out. It builds each one from your own resume, because the generic version is the one you have already rehearsed.

  • “Give me a 95% confidence interval for the number of taxis in New York City.”
  • “Estimate a Fermi-style quantity and give a 95% confidence interval, remember most people are overconfident.”
  • “How would you sanity-check the order of magnitude of that estimate?”

What this round is judged on

  • Structured thinking · decompose the problem cleanly
  • Numeracy as a sanity check · check the order of magnitude
  • Calibration · honest confidence intervals, not overconfident
  • Ask why · stay curious about assumptions

Where this round sits

Jane Street’s published process. Lime marks the stage this round runs.

  1. 01
    Application
  2. 02
    Phone interviews (remote)
  3. 03
    In-person final round (onsite)this round
  4. 04
    Decision
What happens in each stage›
Application
Rolling basis, no deadline. No GPA or degree requirement; interns come from 70+ universities. Jane Street says you can expect to hear from a recruiter within a few days.
Phone interviews (remote)
One or more remote interviews to start. For trading these are conversational probability/logic and market conversations with an actual quant trader; for SWE they are live coding. The interviewer calls you (Zoom if connectivity is poor).
In-person final round (onsite)
The final stage is in person: multiple back-to-back interviews mixing probability, a market-making game, estimation, a light coding/data-analysis chat, and fit. Jane Street books and pays for travel and hotel; interviews run weekdays only, dress casual.
Decision
Jane Street says you should hear back within about a week after the final stage. Reapplication is explicitly allowed (recommended wait ~1 year).

Sources

Built from what Jane Street publishes about its own process and from real interview data. No leaked question lists. The questions you get are generated against your own resume, so they are not from anyone else's interview.

Sources last checked . Hiring loops change, so this date is the honest limit on everything above.

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