What to Expect from a Flow Traders Interview
Flow Traders is one of the world's largest ETF market makers. Founded in Amsterdam in 2004 by two ex-Optiver traders, the firm now has offices in Amsterdam, New York, Hong Kong, Singapore and Cluj, and is publicly listed on Euronext Amsterdam. Flow's business is built on providing continuous liquidity in ETFs across global markets, which means the interview process focuses heavily on probabilistic thinking, mental arithmetic, and an intuitive grasp of cross-listed instruments.
This guide covers Flow's process for trader and software developer roles, the question types that come up most often, and a four-week preparation plan that maps onto the Quantt coding tests.
Flow Traders at a Glance
- Founded: 2004 by Roger Hodenius and Jan van Kuijk
- Headquarters: Amsterdam, Netherlands
- Size: ~700 employees globally
- Listing: Public, Euronext Amsterdam (FLOW)
- What they trade: ETFs primarily, plus the underlying equities, futures and options used for hedging
- Roles they hire: Trader, Quantitative Researcher, Software Engineer, Trading Operations
- Application route: careers page or via the Flow Traders firm page on Quantt
For broader context, see our Flow Traders firm guide and the Amsterdam quant jobs page.
The Interview Process
Stage 1: Online Assessment
A 60-minute timed test. For trader candidates, mental maths and probability questions. For engineers, two HackerRank-style problems in 90 minutes.
Stage 2: First-Round Interview
A 45-minute virtual interview, usually with one trader and one HR business partner. Trader candidates face brain teasers and a short market discussion. Engineers face live coding.
Stage 3: Onsite Super Day
For European candidates, a full day in Amsterdam. For US candidates, in New York. Four to five back-to-back interviews of 45 minutes plus a trading game where you make markets on a series of payoffs.
How Interviews Differ by Role
Trader
The most-hired role. Heavy on mental maths, probability, and decision-making. Flow's twist: more of the discussion centres on cross-market arbitrage and the mechanics of ETF creation/redemption than at SIG or Optiver.
Typical split: 35% mental maths, 30% probability, 25% market intuition (especially ETF mechanics), 10% behavioural.
Quantitative Researcher
A more academic version. Heavier on statistics and Python. Expect questions on signal design, time series, and the practical realities of ETF arbitrage.
Software Engineer
A FAANG-style technical interview with a low-latency twist. C++ is heavily favoured for hot-path systems; Python and Java for platform work.
Real Question Types
Mental Maths
Question 1: What is 14 * 28? Approach: 14 * 28 = 14 * 30 - 14 * 2 = 420 - 28 = 392.
Question 2: What is the square root of 169? Approach: 13. Memorise the squares from 1 to 30 - this comes up constantly.
Probability
Question 3: Conditional You have a bag with three coins. One is fair, one has heads on both sides, one has tails on both sides. You pick one at random and flip it. It comes up heads. What is the probability the other side is also heads?
Approach: Bayes. P(both heads | one heads) = P(2H) * P(H | 2H) / P(H) = (1/3 * 1) / (1/3 * 0.5 + 1/3 * 1 + 1/3 * 0) = (1/3) / (1/2) = 2/3.
Question 4: ETF arbitrage A US-listed ETF tracks the EuroStoxx 50. The ETF's NAV is 50.00. The ETF trades at 50.10 in the US. The EuroStoxx futures imply a fair value of 50.05 for the basket. The Euro is at 1.10 to the dollar. As a market maker, what would you do?
Approach: The ETF trades at a 10-cent premium to NAV but only a 5-cent premium to the implied basket. Sell the ETF (short), buy the underlying basket via futures, and use the creation mechanism to deliver baskets in exchange for ETF shares. Pocket the spread minus transaction costs and currency-hedging cost. The interviewer is testing whether you can think through the full arbitrage chain quickly.
Trading Game
Question 5: I will roll five fair dice. I'll pay you the median value in pounds. Make me a market.
Approach: The median of five uniform draws from {1..6} has expected value 3.5 by symmetry. A reasonable starting market is 3.0 at 4.0. If I trade with you and then immediately want to trade more on the same side, suspect I have information - tighten and skew.
Coding (Engineer)
Question 6: Top-K elements Given a stream of integers, return the K largest seen so far on demand.
Approach: Maintain a min-heap of size K. On each new element, if it's larger than the heap minimum, pop and push. O(log K) per insert, O(K) to read out top K.
How to Prepare - A Four-Week Plan
Week 1: Mental maths. Daily 30-minute Zetamac drills. Target 50+ correct in two minutes by end of week.
Week 2: Probability and brain teasers. A Practical Guide to Quantitative Finance Interviews (Xinfeng Zhou) chapters 1 to 6, plus Heard on the Street.
Week 3: ETF mechanics and options theory. Read about ETF creation/redemption (Vanguard publishes excellent primers), and the first half of Options, Futures and Other Derivatives (Hull). Understand the Greeks intuitively - see our Greeks and volatility in options guide.
Week 4: Mock trading games. Practise market-making with a study partner. Simulate ETF-vs-basket spread trades with realistic transaction costs to internalise how Flow actually makes money.
What Flow Looks For Beyond Technical Skill
Flow's culture sits between the academic intensity of Optiver and the more straightforwardly commercial atmosphere of US prop firms. Two traits matter most.
Speed without recklessness. Flow's trading is high-velocity but the firm is conservative on risk. Candidates who quote prices fast but adjust confidently when shown new information do well. Candidates who quote fast and refuse to update do not.
Comfort with continuous trading. Flow is a market maker by definition - the desks never stop quoting during the trading day. Candidates who are excited by the rhythm of constant price-making outperform candidates who prefer longer-duration, less frequent decisions.
For broader context on the skills firms across the industry value, see our quantitative analyst career guide.
Compensation & recruiting notes
Pay ranges in this guide are illustrative estimates from publicly discussed bands and anecdotal reports - not official figures from the employer. Packages vary widely by desk, office, performance, and year. Hiring processes change; nothing here guarantees an interview, assessment format, or offer.
Frequently Asked Questions
How hard is it to get a Flow Traders interview?
Competitive. Flow hires roughly 30 to 50 graduate traders per year globally. Campus recruiting is heavy at TU Delft, Erasmus, Cambridge, Oxford and Imperial in Europe.
Does Flow hire from non-target universities?
Yes, particularly via the OA. The online assessment is meritocratic and strong scorers are interviewed regardless of school.
What programming languages should I know for a Flow Traders interview?
For trader roles, no programming required at interview. For engineering roles, C++ is heavily favoured.
How does Flow's compensation compare to Optiver and IMC?
The three Amsterdam firms are broadly comparable. Graduate traders typically receive €120,000 to €180,000 in Amsterdam, $180,000 to $250,000 in New York. Senior traders and partners earn substantially more, with Flow's listed status meaning some compensation comes in stock. See our quantitative analyst salary guide.
How many interview rounds does Flow have?
OA, one phone screen, and an onsite Super Day with four to five interviews plus a trading game. Total time from application to offer is typically 4 to 6 weeks.
What is the difference between Flow Traders and Optiver?
Both are Amsterdam-based and both come from the same lineage (Flow's founders are ex-Optiver). Optiver is broader (heavy in options as well as ETFs); Flow is more focused on ETFs. Optiver is private and partnership-style; Flow is publicly listed. Cultures differ marginally - Optiver is typically described as more academic, Flow as more commercial. We have a dedicated Optiver interview guide.
Can I reapply if rejected?
Yes, after 12 months. Flow takes repeat candidates seriously, particularly those who can show measurable improvement in mental maths speed.
Practise the questions Flow Traders Interview: Process, Questions and How to Pass 2026 actually asks
Reading about the interview is one thing - sitting one is another. Quantt's interactive coding tests are modelled on the same problem types that show up in firms like Jane Street, Citadel, Hudson River and Optiver. Run real Python in the browser, get instant feedback, and benchmark yourself against the bar.
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