Interview Experiences

Real candidates, real loops: every round, what was asked, and how it ended.

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6 stories

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Citadel SecuritiesSoftware Engineer
Oct 2026

Stock Returns and a Quick Rejection

My hour-long Citadel Securities Research Engineer interview began with about ten minutes of introductions and an explanation of the team's work. The role used machine learning and quantitative methods to study stock returns. One verbal question compared modeling one-minute and five-day returns. It was broad, with little guidance, and I felt the interviewer was assessing how I structured my thinki…

RejectedTechnical Screen0
Citadel SecuritiesResearch Engineer
Sep 2026

I Built a Transformer When a Decision Tree Would Do, Then Got Ghosted

I work in tech. Every time I get ready to switch jobs, a pile of workload drags me back, so I just kind of go with the flow. Three months ago (I had 4.5 YOE at the time), a recruiter reached out saying some trading companies could do 3-days-a-week hybrid in Florida. Then the team they actually lined up didn't match the pitch lol, they said it was New York only. I wasn't that interested and honest…

No responseTechnical Screen0
Citadel SecuritiesSoftware Engineer
Sep 2026

Trade Data and Timestamp Precision

The author reports a Citadel Securities process with an initial recruiter screen and two technical interviews, without an online assessment. A New York team lead conducted a one-hour session involving trade reconciliation, behavioral questions, and design follow-ups. A London lead then held a longer-than-scheduled interview combining another trade-data task with detailed resume discussion. The ac…

RejectedTechnical Screen0
Citadel SecuritiesSoftware Engineer
Sep 2026

Lock-Free Producer-Consumer, Currency Arbitrage, and an Order Book

Implement a threaded producer-consumer, optimize from a mutex and then a spin lock. A list of currency conversions: determine if an arbitrage opportunity exists. Find the sequence of conversions to make money. Implement an order book data structure: maintain the order of incoming ask/bid/qty price, aggregate. Cancel an order without impacting other orders. Implement a smart queue: maintain the or…

Onsite0
Citadel SecuritiesQuantitative ResearcherIntern
Aug 2026

Six Weeks after a Virtual Onsite

I interviewed with a small Citadel Securities alpha-capture team in New York. There was no online assessment. Two technical interviews covered my doctoral research and internship projects, and subsequent interviews were arranged quickly, often the same day. An internship conflict prevented an in-person onsite, so I completed four virtual rounds. One explored ordinary least squares, lasso, and rid…

RejectedOnsite0
Citadel SecuritiesQuantitative TraderIntern
Nov 2025

Dice-Product Probabilities and a Live Trading Round

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Technical ScreenXP0

What are interview experiences?

An interview experience is a candidate's own account of a hiring loop — not a question bank entry. It tells you the shape of the process: how many rounds there were, what each round actually tested, how long the gaps between them ran, and what the recruiter said at the end. That context is the part a question list cannot give you.

How to read them

Weight recent write-ups more heavily — interview loops change, often within a year. Read several for the same company and role rather than one: a single account tells you what one interviewer asked, while five tell you what the bar is. Note the outcome badge too, since a rejection write-up usually explains the gap far more precisely than an offer one.

Share your own

Every published experience earns 50 XP, and each of the first 3 likes it receives in a day earns you 10 XP more. Likes must come from established accounts; like-for-like swaps and likes from your own second account are not paid. Write it while the details are fresh — the round order, the exact prompts, and how much time you were given are what the next reader needs.

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