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.

01
Application
02
Phone interviews (remote)
03
In-person final round (onsite)this round
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.

companyJane Street, How We Interviewjanestreet.com
Two-stage process, conversation-not-a-quiz philosophy, any-language coding and OCaml guidance, logistics and reapplication
companyJane Street, Trading Interviewsjanestreet.com
Trading two-stage structure, final-round content, desired traits, four principles, myth-busting on mental math and theorems
companyJane Street, Probability & Markets guide (PDF)janestreet.com
Trading interview syllabus, verbatim example probability/EV questions, market-making game prompts and quoting jargon, adverse selection
companyJane Street, Join overviewjanestreet.com
Company blurb, roles, 'smart people with curious minds from any background'
companyJane Street, SWE mock interview videojanestreet.com
Official software-engineering mock interview walkthrough referenced by the interviewing page
datalevels.fyi, Jane Street salaries & levelslevels.fyi
Confirms Jane Street SWE levels (L1-L4) and titles including Quantitative Developer and Full-Stack Software Engineer

Sources last checked August 10, 2026. Hiring loops change, so this date is the honest limit on everything above.

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