Katkat

Company

Citadel Securities interview questions

4 practice questions in the style of Citadel Securities's interviews, covering Software Engineering Fundamentals.

Questions4

0 easy4 medium0 hard

Your progress0/4

Citadel Securities interview questions by the numbers

Last updated

Katkat has 4 Citadel Securities interview questions. The largest topics are Software Engineering Fundamentals (100%). By difficulty: 100% medium. The most common round is Onsite (50%).

Topics

Difficulty

  • Medium100% · 4

Interview rounds

  • Onsite50% · 2
  • Technical Screen50% · 2

Roles

  • Software Engineer100% · 4

Most mentioned in interview experiences

  1. 1.Define a Reliable Trade-Reconciliation Library Contract1 report
  2. 2.Design a Top-Ten Trade Query with Exact Amounts1 report
  3. 3.Detect Currency Arbitrage and Return a Profitable Conversion Cycle1 report
  4. 4.Thread-Safe Producer-Consumer Queue: Mutex, Then Spin Lock, Then Lock-Free1 report

Counted from 2 candidate interview experiences on Katkat. How we collect and count

Showing 1–4 of 4 results

  • Define a Reliable Trade-Reconciliation Library ContractMedium

    Define trade-reconciliation contracts and OOP boundaries with exact values, timestamp tolerance, partial-fill questions, deterministic policy ownership, and traceable breaks.

    Citadel SecuritiesSoftware EngineerSoftware Engineering FundamentalsTechnical Screen
  • Design a Top-Ten Trade Query with Exact AmountsMedium

    Design a top-ten trade query around an explicit ranking contract, exact monetary aggregation, bounded heaps, timestamp boundaries, and mutable-score streaming tradeoffs.

    Citadel SecuritiesSoftware EngineerSoftware Engineering FundamentalsTechnical Screen
  • Detect Currency Arbitrage and Return a Profitable Conversion CycleMedium

    Given a list of currency conversion rates, determine whether an arbitrage opportunity exists and return a sequence of conversions that ends in the starting currency with more money than it began with. Tests graph modeling, cycle detection, reconstruction of the profitable sequence, and handling of floating-point precision.

    Citadel SecuritiesSoftware EngineerSoftware Engineering FundamentalsOnsite
  • Thread-Safe Producer-Consumer Queue: Mutex, Then Spin Lock, Then Lock-FreeMedium

    Implement a thread-safe producer-consumer queue in C++, first with a mutex, then with a spin lock, then as a lock-free design with explicit memory ordering. Tests the C++ memory model, contention and cache effects, blocking versus spinning, and where memory is allocated on the hot path.

    Citadel SecuritiesSoftware EngineerSoftware Engineering FundamentalsOnsite

Citadel Securities interview experiences

All 3 →
  • I Built a Transformer When a Decision Tree Would Do, Then Got GhostedCitadel Securities · Research Engineer · Technical Screen · Sep 2026
    No response

    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…

  • Lock-Free Producer-Consumer, Currency Arbitrage, and an Order BookCitadel Securities · Software Engineer · Onsite · Sep 2026

    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…

  • Trade Data and Timestamp PrecisionCitadel Securities · Software Engineer · Technical Screen · Sep 2026
    Rejected

    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…

More companies