Quant Interview Question Types
A guide to the main quant interview question types: probability, expected value, statistics, market making, mental math, coding, and communication.
Candidates trying to understand what to practice for quant trading, research, developer, or internship interviews.
Probability and counting
Probability questions test whether you can define outcomes, condition correctly, and count without double-counting. Coins, dice, cards, urns, Bayes rule, and random walks all sit in this bucket. The surface story changes, but the method is usually sample space, complement, symmetry, recursion, or conditioning.
Expected value and decision questions
Expected value questions ask what an uncertain payoff is worth. In trading interviews, the same skill often becomes a bet, quote, or sizing decision. The interviewer may care as much about your risk discussion as the numeric expectation, especially when variance, bankroll, or repeatability matters.
Statistics and research judgment
Statistics questions cover distributions, variance, covariance, regression intuition, sampling error, and experiment design. Research-style interviews also test whether you can critique evidence. A strong answer names assumptions and says what data would make the conclusion more or less credible.
Market making, games, and estimation
Trading games test decisions under uncertainty. You may estimate a fair value, set a bid and ask, update after trades, or manage inventory. Estimation prompts test the same discipline in another form: state assumptions, produce a plausible range, and revise when new information arrives.
Coding and implementation
Quant developer and many research roles include coding prompts. Expect data structures, algorithms, debugging, small simulations, or data manipulation. The key signal is not only reaching an answer, but writing clear logic, checking edge cases, and explaining complexity.
Common mistakes
Candidates often prepare only one question type because it feels comfortable. A puzzle-heavy plan misses statistics, coding, and communication. A coding-only plan misses probability and expected value. Use question types as a coverage map, then spend more time where your diagnostic is weakest.
Practice the pattern
Use the LeetQuidity curriculum and calibration to turn this topic into a focused practice plan.