Five Rings Interview Process & Prep
Five Rings filters almost entirely on a timed mental-math / estimation screen (webcam on, ~1–3 min per question, no calculator), then layers technical phone rounds with quant researchers and traders. The QT signature is escalating dice/betting-DESIGN game rounds (design a custom die, dice-vs-deck covariance, random-walk EV bounds); the QR path adds a data project. Replies are slow and the full-time bar is brutal.
The Five Rings interview funnel
1. Timed Mental-Math Screen
~17–30 min · webcam · no calculatorThe dominant filter — an OA or an HR-read live screen. ~17–20 questions in ~17–30 minutes (QR: ~12–16 with per-question timers), webcam on, fill-in-the-blank, answer to the nearest integer. Content: mental math, probability, estimation, light calculus (arc length), modular arithmetic. The QT version also has a behavioral intro ('why trading / why Five Rings') and a Fermi-estimation section.
2. Technical Phone
45–60 min · with a QR / traderDeeper probability and statistics with a quant researcher (often a math PhD who hints heavily): variance of a coordinate of a random point on a sphere, P(X+Y > XY) for two dice, the broken-stick longer-piece expectation, random-walk hitting probabilities, the signature bus-stop residual-life waiting-time problem, and regression facts (Y~X vs X~Y slope bounds, σ_{X+Y} → correlation).
3. Dice / Betting Game Round (QT)
Interactive · with a traderThe trader signature: escalating game-DESIGN problems. Design a custom die (faces summing to 21) to maximize your win rate against an opponent using the same die; then asymmetric-die variants; then die-vs-deck comparisons reasoning about negative covariance from sampling without replacement; plus random-walk EV-bound problems. It's pure EV intuition under rising complexity. Rehearse the muscle with the games below.
4. Second Technical Phone (QR)
45–60 min · estimation / inferenceThe QR second round leans on estimation and inference: MLE for n iid U(0,θ), confidence intervals (normal-unknown-variance vs distribution-free), the 'sum of U(0,1) first exceeds 1' result (E[N] = e) with its variance and CI, mean-vs-median comparisons via Jensen, and geometric-probability problems.
5. Data Project (QR)
Take-home · NDAA QR-specific take-home dataset project (NDA-covered, so details are scarce). Weak performance here is a common reject reason — it's a real gate, not a formality.
6. Final Rounds
Head of trading → 'boss'The closing sequence — a head-of-trading round and then a 'boss' final. More probability/EV plus fit, with the same friendly-but-high-bar vibe. The full-time bar is reported as brutal.
Five Rings interview — FAQ
What is the Five Rings interview process?
Five Rings filters almost entirely on a timed mental-math / estimation screen (webcam on, ~1–3 min per question, no calculator), then layers technical phone rounds with quant researchers and traders. The QT signature is escalating dice/betting-DESIGN game rounds (design a custom die, dice-vs-deck covariance, random-walk EV bounds); the QR path adds a data project. Replies are slow and the full-time bar is brutal. The loop runs 6 stages: Timed Mental-Math Screen, Technical Phone, Dice / Betting Game Round (QT), Second Technical Phone (QR), Data Project (QR), Final Rounds.
How many rounds does Five Rings have?
6 stages in total, starting with the Timed Mental-Math Screen and ending with the Final Rounds.
How do I prepare for the Five Rings interview?
Work the stage notes above, then drill the Five Rings interview-questions set and the Five Rings online-assessment practice — each problem has a full worked solution.