Flow Traders Interview Questions
Probability, expected value, fast mental math, ETP and market-making microstructure, and clean coding — the mix Flow Traders screens for in its trading and dev loops.
Inside the Flow Traders interview
Flow Traders is an Amsterdam-rooted algorithmic market maker in exchange-traded products (ETFs, ETPs, and increasingly crypto). Its interviews emphasize speed under uncertainty: tight mental arithmetic, expected-value reasoning, and an instinct for how two-sided quotes and ETP mechanics actually behave.
What they test
The core is probability and expected value — fair-value bets, conditional updates, and expectation of dice, coins, and stopping rules. Around it sits a market-making and ETP layer (two-sided quotes with overround, make-or-take decisions, leveraged-ETF rebalancing, arbitrage and price impact) and a clean-coding block for the developer track, from prefix sums to an order-matching engine.
The recurring shapes
Expect quick EV games (guess-the-suit, lopsided-coin bets, roll-until-exceed), Bayesian updates from a trade or a noisy signal, and fast mental math brain-teasers (powers mod a prime, ratios near one-half, sequence puzzles). The finance set leans concrete: overround in a two-sided market, delta and path-dependence, VaR, and how a 3x oil ETF drifts as it rebalances.
How to approach
Quote a price fast, then defend it: state your fair value, size the edge, and reason about adverse selection before you widen. For the coding track, write the obvious correct solution first (two heaps for a streaming median, modified merge sort for inversions) and only then optimize. Narrate the arithmetic — they want to hear the estimate, not just the answer.
The mix leans medium, with a strong band of easy mental-math and EV warm-ups and a hard tail in options-pricing, Gaussian probability, and the order-matching-engine coding problem.
Flow Traders coding questions (10)
- Balanced Job Scheduling: Max Jobs on the Fast Processor
- Second Largest Distinct Value
- Balanced Brackets
- Recover the Matrix From Its 2D Prefix Sums
- Find the Extra Letter After a Shuffle
- Aho-Corasick Multiple-Pattern Matching
- Sliding Window Median with Two Heaps
- Counting Inversions via Modified Merge Sort
- Count Subarrays Divisible by m
- Reverse a Singly Linked List In Place
Flow Traders expected value questions (10)
- Expected Value of a Lopsided Coin Bet
- Expected Product of Two Independent Dice
- Expected Triangle Area on a Unit Sphere
- Expected Sum When Rolling Until Exceeding Four
- Conditional Expectation of Brownian Motion Given Its Absolute Value
- Expected Hitting Time with Uniform Starting Point
- Expected Rolls with a Fair Die
- Standard Normal MGF and Even Moments
- Guessing the Suit: An Expected-Value Card Game
- Expected Flips to Get k Heads
Flow Traders probability questions (9)
Flow Traders brain teasers questions (6)
Flow Traders combinatorics questions (6)
Flow Traders finance questions (5)
Flow Traders options pricing questions (4)
Flow Traders market microstructure questions (2)
Flow Traders random variables questions (1)
Flow Traders interview FAQ
What kind of questions does Flow Traders ask in quant interviews?
Candidates most often report coding, expected value and probability questions. This page collects 53 of them, 15 stamped with the month they were last reported — each with a full worked solution.
How hard are Flow Traders interview questions?
The set spans 14 easy, 29 medium and 10 hard problems. Most sit at medium difficulty — solvable in a few minutes with clean reasoning — with a harder tail that rewards knowing the canonical tricks.
How do I prepare for the Flow Traders quant interview?
Work through this set by topic (use the sidebar), starting from your weakest area. 5 problems are free to open with their full solution, so you can judge the quality before anything else. Then walk the full Flow Traders interview guide for the round-by-round funnel and the online assessment.
Are these the actual Flow Traders interview questions?
They are built from candidate-reported Flow Traders questions. We rewrite each prompt for clarity and author the worked solutions ourselves — we don't claim the wording is verbatim, and we never invent questions or recycle generic lists. 15 of 53 carry the month they were last reported.