Jane Street interview notes, page 6 of 6

Large Enterprises

Most of these Jane Street write-ups come from Software Engineers (25), then Data Scientists (17) and Machine Learning Engineers (10). The most reported rounds are the technical phone screen (44), the system design round (6), the onsite coding round (3) and the recruiter screen (1).

54 interview notes · updated Jul 2026

Jane Street·Data Scientist·Technical Phone Screen

Jul 2026

Jane Street data scientist interview with a pretty gnarly probability/game theory problem. One question, no fluff, just math and reasoning under pressure.

You roll a fair six-sided die repeatedly, accumulating a running sum. You can stop anytime and collect the current sum, but if the sum ever hits a perfect square (1, 4, 9, 16, ...) you lose everything and get zero. There's no roll limit. What's the optimal stopping strategy, and what's the expected payoff under that strategy starting from zero?

“This one wrecked me for the first few minutes.”

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Jane Street·Software Engineer·Recruiter / HR Screen

Jul 2026

Recruiter screen for a software engineer role at Jane Street. Just one question from what was shared, a standard motivation question, but Jane Street puts real weight on these so it's worth thinking through.

Why Jane Street? Walk us through what draws you to this firm and this role specifically, with concrete examples from your background.

“They want specifics, not vibes.”

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Jane Street·Machine Learning Engineer·Technical Phone Screen

Jul 2026

Jane Street ML Engineer interview, one meaty technical question that was basically a full project scoped into a single session. Felt more like a design review than a coding screen.

Given a time-series dataset, build an end-to-end ML solution to forecast future values. Walk through your model architecture choice, how you'd implement the training loop in PyTorch, and how you'd evaluate it.

“This is a lot to hold in your head at once.”

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Jane Street·Software Engineer·Technical Phone Screen

Jul 2026

Jane Street software engineer interview with a probability brain teaser. The kind of question where you either see the structure quickly or spend five minutes going in circles.

In a three-player dice game where each person rolls a standard 6-sided die and the highest roll wins (with ties broken by re-rolling among tied players), your two friends have both rolled a 4. You roll next. What is the probability that you eventually win?

“I stared at this longer than I'd like to admit.”

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