Citadel Securities
Quantitative Trader intern
Application
One application covers trading and research, with two rotations over the summer. The form asks for your top two interview languages and any competing deadlines, and recruiters follow up for GPA and return-offer dates. The CV screen is strict and noisy.
Online assessment
Web form · 30 min, 15 items
About fifteen short probability word problems in thirty minutes, each wanting one number: no multiple choice, no working, no coding for traders. Sat in the 2023–25 cycles; US candidates for Summer 2027 went straight to Round 1.
Sit this round →Round 1
Virtual interview · 45 min
Zoom with one trader and a CoderPad link that mostly goes unused. A few minutes on your background, then one long problem the interviewer keeps extending: an expectation, a confidence interval with "are you really 90% sure?", a market cut from that interval and traded for four rounds, your P&L and what the trades told you. A short geometric-probability question fills the last ten minutes.
Sit this round →Round 2
Virtual interview · 45 min
Another trader on Zoom, another CoderPad link, and this time whether you code is the interviewer's call: either half probability and half Python simulation, or only brainteasers. Expect a game-theory question and a Fermi estimate run as an interval, then a market, then "how much did you make or lose?"
Sit this round →Superday: group game
In-person interview · ~1 hour
In person in New York, often on a Friday, with about eight candidates. The day opens with a group market-making game against each other: two cards each that you never see yourself, one of each neighbour's cards that you do, cards in the middle turned over between rounds, and each round the table bids for the narrowest width; the winner makes the market and everyone else trades on it, up to twenty lots. Afterwards the traders question the table: what would have happened if a different card had come up, what you would do with far more cards in play, how to play with no edge.
Sit this round →Superday: interviews
In-person interview · 3 × 45–60 min
Three one-on-one interviews back to back: probability and expected value with the arithmetic done out loud; an order book the interviewer puts up and keeps changing, with questions on fair value, filling an order, where your own bid sits in the queue and what the flow says, after a few questions about you; and a game against a trader: a hidden three-region spinner where you pay to spin or pay more to guess the sizes, are told only how many guesses are right, and end by saying what the game was worth.
Decision
About a week when it comes; silence is common, and processes stop once headcount is reached. Very few offers are made per cohort.
Reconstructed from first-hand candidate reports and the firm's own published material. Problems in this track are original and format-faithful; nothing is copied from a live interview.