Citadel Securities vs Citadel
Citadel Securities is the market-making arm spun off from Ken Griffin's broader Citadel franchise. While Citadel LLC is a multi-strategy hedge fund, Citadel Securities is a high-volume electronic market maker quoting in equities, options, fixed income, FX, and crypto. The two firms hire separately, run different interview processes, and look for different profiles. If you want hedge-fund quant research, see our Citadel hedge fund guide; this post focuses on the market maker.
Interview Process
- Online assessment: timed math + coding (HackerRank format)
- First round: phone screen with a quant trader or engineer
- Final round: on-site or virtual super-day with five to seven interviews
The pace is fast — most candidates get a final-round decision within ten business days of the first phone screen.
Probability and Markets Game
Citadel Securities runs a market-making round in nearly every quant-trader and quant-developer interview. You'll be asked to quote a bid-ask spread on something — a hidden number, a coin-flipping process, the sum of dice — and the interviewer will trade against you while changing the parameters. They're testing how you update under uncertainty, manage your risk, and price your edge.
Coding and Systems
For engineering roles, expect C++ at production depth. Topics include cache-friendly data structures, atomics, lock-free programming, kernel-bypass networking, and FPGA basics. Citadel Securities' edge depends on microsecond-scale performance, so they care a lot about whether you understand why a piece of code is fast, not just whether it works.
For Trader Candidates
Trader interviews emphasize:
- Mental math under time pressure
- Probability puzzles with adversarial twists
- The market-making game across multiple rounds
- Brief market intuition questions (e.g., "what happens to vol when the Fed cuts unexpectedly?")
Behavioral
Citadel Securities is high-intensity, but interviewers are direct rather than aggressive. Expect questions about how you handle being wrong, how you make decisions with incomplete information, and what you'd do if your team disagreed with your call.
How to Prepare
- Get fast at mental math — use our mental math game
- Practice the market-making round — try our card-counting game for decision-under-uncertainty practice
- For engineering, study modern C++ (Effective C++, Modern Effective C++) and Linux performance fundamentals
- Read about market microstructure if you're going for a trader seat