A common point of confusion clears a lot up: Citadel (the multi-strategy hedge fund) and Citadel Securities (the market maker) are separate companies with their own hiring processes. Both run an early online assessment followed by technical rounds, and both prize precise quantitative reasoning — but you should tailor your prep to the specific firm and role.
What the interviews test
Across both firms, expect probability and statistics worked rigorously, brainteasers that reward structured reasoning, and — for technical tracks — programming and data structures. The emphasis differs by track:
| Track | Leans on |
|---|---|
| Trading | Probability, expected value, mental math, brainteasers |
| Quant research | Deeper statistics and probability, modelling |
| Engineering / quant dev | Coding, data structures, systems |
Key insight. What unites every track is a high bar for clear, precise reasoning rather than memorised tricks. Citadel would rather watch you derive a result cleanly than hear a formula you can't justify.
How to prepare
- Build broad probability and statistics fluency — the common core across tracks.
- Drill brainteasers and practise explaining your reasoning aloud.
- For technical tracks, keep your programming and DSA sharp.
- Simulate the timed screen with the Probability OA.
When you are ready, work the Citadel question set. For another research-and-coding shop to compare against, see the Two Sigma guide.