I applied through university. I interviewed at Citadel Securities in Nov 2024
Interview
first there were two very hard C++ hackerrank questions
next there was a technical interview with a bit of C++ trivia and then a combinatorics question. interviewer was very nice, smart and down to earth
Interview questions [1]
Question 1
Given some C++ code samples (including inheritance and different types of references), determine what their expected behaviour should be.
I applied online. I interviewed at Citadel Securities (Sydney) in Jun 2026
Interview
The process includes 4 technical interview and 1 final behavior interview, the primary language is Python. You will scheduled for next round if passed previous round, I failed on 2nd round
Interview questions [1]
Question 1
1st round: questions about tcp/udp, heap, queue, thread/process + coding exercise about parse file
2nd round: ask about project experience, implement decorator
I applied online. I interviewed at Citadel Securities (Chicago, IL) in Feb 2026
Interview
First round is behavioral and technical and second round is superday. Then is final round and team matching. Superday was virtual and 45 min each, all same format, with beginning behavioral questions, a huge chunk on system design, and final questions at the end.
Interview questions [1]
Question 1
System design, create a stock options book using dict
Went through 4 rounds of technical interview + 1 round of leadership round.
This was for a C++ internship role. Process and questions were very dependant on your interviewer, but it is definitely C++ heavy and should be familiar with low level stuff
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