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Citadel Securities Software Engineer Interview Questions

The questions to prepare for a Citadel Securities Software Engineer interview. Questions from real interview reports rank first. Updated daily.

50questions
~8htotal time
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1
CodingStart here. 17 questions · ~169 min
Implement a Simple Stock ExchangeHard
Practice
Recently asked

Match buy and sell orders using price-time priority with heaps, producing trades and the remaining order book.

system designcoding challengeData StructuresCitadel Securities
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2
Security & Infrastructure8 questions · ~80 min
Thread vs ProcessHard
Recently asked

Explain thread and process isolation, resource ownership, communication, and the security trade-offs between them.

Operating SystemsprocessesconcurrencyCitadel Securities
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3
Execution10 questions · ~99 min
Process Time and API DesignHard
Recently asked

Estimate a process duration and design an API that exposes progress, completion, and timing information.

api designExecutiondelivery managementCitadel Securities
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4
System Design4 questions · ~40 min
Citadel Securities Project Deep DiveHard
Recently asked

Assesses ability to connect technical choices to performance in market modeling.

distributed systemsData StructuresFinancial ModelingCitadel Securities
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5
Technical Fundamentals3 questions · ~30 min
Wait-Free GPU EnablersMedium
Recently asked

Assesses your understanding of concurrency and systems concepts relevant to modern hardware.

innovationtechnical knowledgeCitadel Securities
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6
Behavioral & Leadership5 questions · ~50 min
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7
More topics3 questions · ~30 min
Class Design QuestionHard
Recently asked

Design a focused, testable class for a coding interview problem with clear responsibilities, interfaces, validation, and replaceable solution strategies.

Testabilitydesign patternsarchitectureCitadel Securities
Multicast and Exchange Data ConsistencyHard
Recently asked

Evaluates distributed data consistency reasoning and correct aggregation logic.

Citadel Securities
Data Processing and Job ExecutionMedium
Recently asked

Evaluates your approach to building reliable pipelines and orchestrating job execution.

data processingExecutionCitadel Securities
Hands-on SQL practiceWrite and run real queries in the editor. 3 drills · ~30 min
Handling Missing DataEasy
Practice
Practice drill

Replace missing sales fields with defined defaults and return a consistently ordered dataset.

missing valuesdata cleaningnull handlingUniversity of MinnesotaThe Home DepotNationwide
Unique Elements and Top-K FrequenciesMedium
Practice
Practice drill

Return the first row for each unique value, then rank the k most frequent values.

large datasetsData Structurescomplex queriesEverlaw
7th Nearest Palindrome CodingHard
Practice
Practice drill

Return the seventh closest palindrome for each valid input number, using recursive query logic and ordered ranking.

Dynamic ProgrammingCTEscomplex queriesDeloitte
The finish line: interview-readyComplete all 50 questions plus 3 hands-on drills to finish this plan.