I applied online. I interviewed at Citadel (London, England) in July 2025
Interview
45 minute interview (15 min CV, 30 min maths), questions about linear regression, lasso, ridge... And optimization. Many maths questions during the interview: probability, linear algebra, and calculus. The interview is easy but the interview questions were tricky.
Interview questions [1]
Question 1
Explain the difference between the Lasso and the Ridge?
- Questions on Linear Algebra and Coding
- Discussion of a problem at the intersection of optimization and classical machine learning
- No behavioural questions or anything about my personality or work experience, the interview was purely technical
Interview questions [1]
Question 1
- Explain how to compute a product of two very large matrices in a computationally efficient way, using the structure of the problem and the matrices
Start with my own self-introduction and the interviewer's self-introduction first for five minutes, then a couple of technical questions for like thirty minutes, and in the end, questions for the interviewers about the company.
I received the interview a few weeks after applying online. During the interview i was asked by the interviewer about my past experience and also some other related technical questions.