Optiver interview prep
Optiver interviews emphasise arithmetic speed and probability fluency. QuantPrep builds both.
TRY A PROBLEM NOW · NO SIGNUP
In the classical secretary problem, as n → ∞, what fraction should you reject outright before accepting the next best-so-far candidate?
WHAT OPTIVER FOCUSES ON
- ·80in8 mental math test (or similar speed screen)
- ·Probability and expected value brainteasers
- ·Trading-style puzzles (market-making estimation)
- ·Game theory on repeated games
- ·Quick reasoning under time constraints
INTERVIEW OVERVIEW
Optiver is the firm most famous for its arithmetic screen. The 80in8 test — 80 mental arithmetic problems in 8 minutes — is the first filter for almost every candidate, and its reputation is earned: candidates who haven't trained specifically for it fail. Past the speed screen, the interview process pivots to probability, trading brainteasers, and market-making case studies. Optiver's culture is competitive, fast, and trading-focused; interviews reflect that. Expect to be interrupted, asked to justify each step, and thrown curveballs to test how you react under mild pressure. Candidates who pass typically arrive with two pre-built assets: a baseline arithmetic fluency that gives them headroom on the speed tests, and a library of probability patterns deep enough that most standard problems decompose within a few seconds. QuantPrep cannot replace the arithmetic drilling — that requires a separate tool. But it covers every probability and expected-value pattern Optiver tests, with adaptive selection that concentrates reps on your weakest techniques.
INTERVIEW STRUCTURE
Online screening. 80 arithmetic questions (addition, subtraction, multiplication, division, decimals, fractions, percentages) in 8 minutes. Passing threshold is typically ~60/80 but varies by role and cohort.
A follow-on online assessment focused on probability, logic, and sometimes basic programming. Expected value, conditional probability, and classic dice / coin problems dominate.
One or two video interviews with traders or researchers. Rapid-fire probability questions, a mental math live round, and sometimes a trading estimation question (market-making spreads, EV of a given bet).
Usually on-site in Amsterdam or Chicago. Multiple interviews, includes trading simulation games (live market-making with the interviewer), more probability depth, and cultural fit conversations.
THE THE 80IN8 ARITHMETIC TEST
Eighty mental arithmetic problems — addition, subtraction, multiplication, division — with decimals, fractions, and percentages mixed in. Eight-minute time limit. Almost no candidate passes on talent alone; it requires dedicated training.
Drill daily on arithmetic.zetamac.com with custom settings matching 80in8 style (multi-digit multiplication, decimal division, percentage conversions). Aim for a sustainable score 20% above your target before the test date — stress will cost you on test day. Two to four weeks of daily practice is typical for candidates starting from zero fluency.
The probability and brainteaser portion of the Optiver interview process — not the 80in8 itself. QuantPrep is designed for the harder-to-prepare half: expected value, dice, coin, Markov chain, and market-making estimation problems. Pair it with zetamac or a similar arithmetic tool.
SAMPLE PROBLEM TYPES
Representative of what Optiver interviewers ask. Drill these and their variants on QuantPrep.
I offer you a dice game: roll a fair 6-sided die. You win £ equal to the face shown, but you can choose to re-roll exactly once, in which case you're forced to keep the second roll. What's your strategy, and what's the expected value? (Dynamic programming / backwards induction on a trivial state space — expected value is 4.25.)
I'm thinking of a stock trading at some price between 0 and 100. Quote me a 5-wide market. I can buy or sell at your quote. What should you do? (Tests whether you understand adverse selection — you should quote around 50 but widen if you suspect information asymmetry.)
A standard 52-card deck is shuffled. What's the probability the top card and the bottom card are both aces? (4/52 × 3/51. Tests whether you can sample without replacement cleanly under time pressure.)
I flip two coins behind a screen. I tell you at least one is heads. What's the probability both are heads? (Classic Bayes problem — 1/3, not 1/2. Optiver favourites for testing whether candidates reflexively apply the wrong prior.)
HOW TO PREPARE
- ·Start arithmetic drilling at least 3 weeks before the 80in8 test window. Score ceilings are real — last-minute cramming won't raise them.
- ·Practise on zetamac with decimals and fractions explicitly enabled; don't train only on integer addition.
- ·For the probability test, memorise expected value formulas for geometric, binomial, and simple random walks — they compose into most problems you'll see.
- ·Study market-making intuition: quoting a tight spread when information is symmetric, widening it when counterparties have an edge.
- ·Practise live mental-math answering (not silent calculation) — video interviewers can hear hesitation, and it reads as slow.
- ·Know the classic coin / dice / card combinatorics by heart — Optiver reuses them with small variations.
COMMON MISTAKES
- ×Treating 80in8 as a math test instead of a training exercise. It's a reaction-time test on arithmetic patterns; only repetition moves the score.
- ×Under-practising the probability half. Candidates who pass 80in8 sometimes underestimate the probability screen and fail there instead.
- ×Quoting symmetric markets reflexively. Real trading involves inference from the counterparty's behaviour; interviewers test whether you notice.
- ×Showing frustration when interrupted. Optiver interviewers interrupt on purpose — how you respond matters.
- ×Forgetting to restate assumptions. Answers without stated assumptions are unverifiable.
FAQ
An online arithmetic test: 80 questions in 8 minutes — addition, subtraction, multiplication, division with decimals. Passing scores are typically 60+. Practise on separate arithmetic tools.
Expected value problems, dice / card probability, Markov-chain style reasoning, basic Bayes, and trading-specific estimation. QuantPrep covers all of these.
Not directly — Optiver's 80in8 is a specialised speed test. QuantPrep covers the probability and brainteaser portion of the interview process, which is the harder part to prepare for.
Low single-digit percent acceptance rates are standard for trading roles out of the 80in8 funnel. Most candidates are eliminated at the arithmetic screen rather than later rounds.
Policies vary by cohort and region. Some intake cycles allow one retake; others treat the first score as final. Don't plan to retake — plan to pass first time.
Typically on-site in Amsterdam or Chicago, multiple back-to-back interviews including a live trading game where you make markets against the interviewer. Probability depth, cultural fit, and trading instinct are all probed.
Yes — Optiver recruits heavily from STEM backgrounds without finance experience. The 80in8 is the democratising screen: if you pass, your background matters less.
COMPARE OPTIVER WITH
Jane Street emphasises reasoning depth and conceptual conversations; Optiver emphasises arithmetic speed and rapid-fire probability. Both are elite — the differences are in what they select for.
Optiver and IMC are the two biggest Dutch-origin quant firms. Both arithmetic-heavy, both probability-focused — but culturally and in intensity they differ.
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