Company interview guide
Jane Street interview guide
Jane Street interviews are uniquely challenging, focusing on probability, mental math, trading intuition, and OCaml/functional programming. They test your ability to think under uncertainty, reason about edge cases, and communicate mathematical ideas clearly.
Use this guide as an execution checklist: align your prep to each round, rehearse examples for behavioral depth, and run timed technical sessions to validate speed and clarity. Most candidates improve faster when they combine targeted study with regular simulation rather than solving questions at random.
Interview process
4 rounds- 0160 min
Phone Screen
Math puzzles, probability questions, and market-making scenarios.
- 023 hours
First Round
Two interviews: coding in OCaml + quantitative reasoning.
- 035-6 hours
Final Round
Multiple rounds: coding, systems, trading games, and behavioral.
- 04Part of final
Trading Simulation
Mock trading game testing decision-making under uncertainty.
Question breakdown
share of loopQuantitative/Math
35%Probability, expected value, combinatorics, estimation
Coding
30%Functional programming (OCaml), algorithms, correctness
Trading/Market Making
25%Market-making games, risk assessment, pricing
Behavioral
10%Collaboration, communication under pressure
Do
5- Practice mental math and estimation problems daily
- Learn OCaml basics - they strongly prefer functional programming
- Study probability theory: Bayes theorem, expected value, conditional probability
- Practice explaining your reasoning out loud - communication is heavily weighted
- Play mock trading games to build intuition about markets and risk
Avoid
4- Not practicing mental math and estimation enough
- Ignoring the functional programming preference
- Being too risk-averse or too risk-seeking in trading scenarios
- Not showing your work - they want to see reasoning, not just answers
Key patterns to master
These coding patterns appear frequently in Jane Street interviews.
Complete your prep stack
Pair this guide with topic practice and timed simulation so you can move from knowledge to interview execution.
Keep a short weekly retrospective with three notes: what improved, what stalled, and what you will change next week. That feedback loop makes company-specific prep more consistent and reduces last-minute cramming.