Citadel Product Designer (Engineering) Case Interview — Real‑Time Trading Risk & Execution Workflow

This case simulates designing a mission‑critical internal tool used by portfolio managers, execution traders, and risk/compliance at Citadel. Expect a fast, data‑dense problem where you must balance latency, clarity, and control under real‑world market constraints. Scenario prompt candidates (interviewer will choose one): - Design a real‑time multi‑asset execution and risk dashboard that helps a PM and trader monitor positions, route orders, act on anomalies, and satisfy auditability requirements. - Reimagine alerting and triage for trade‑surveillance signals to reduce noise while preserving recall during volatile market conditions. - Create a what‑if/impact analysis surface that lets a PM test hedges and liquidity options across venues before placing large orders. Citadel‑specific context you should incorporate: - Speed and precision: interfaces must support sub‑second updates from market/OMS/EMS feeds, keyboard‑first power‑workflows, and unambiguous states. - Data density done right: compress high‑signal info using progressive disclosure (overview → drill‑down), dark‑theme trading floor ergonomics, and minimal cognitive switching. - Quantitative rigor: define measurable success (e.g., time‑to‑decision, execution slippage vs. benchmark, alert precision/recall, MTTD/MTTR for incidents), and propose experiments (shadow mode, simulated markets, desk‑by‑desk rollout). - Risk, compliance, and auditability: permissioning, immutable event trails, explainable alerts, and safe defaults for degraded data (market halts, venue outages, stale ticks). - Collaboration with PMs/quants/engineers: clarify APIs, data freshness, failure modes, and technical constraints (streaming transport, throughput limits, fallback strategies). Expected flow (60 minutes): - 0–5: Clarify objectives, primary users, and the decision moments that matter most to PnL and risk. - 5–15: Map key workflows and edge cases (e.g., volatility spikes, circuit breakers, canceled/partial fills, cross‑asset hedging). - 15–35: Propose IA and sketch low‑fidelity wireframes for: Overview (positions, PnL, exposure), Blotter/Execution panel, Alert Triage, and a What‑If panel. Narrate interaction patterns, shortcuts, and state handling under load. - 35–45: Deep dive trade‑offs (latency vs. visual fidelity; precision vs. recall; global vs. desk‑specific defaults), security/permissions, and audit trail design. - 45–55: Define metrics, experiment/rollout plan, and how you’ll partner with engineering to validate performance (synthetic load, canary desks, kill switches). - 55–60: Risks/unknowns, assumptions made explicit, and quick Q&A. What the interviewer scores highly: - First‑principles framing tied to business impact (not just UI polish). - Mastery of dense data visualization and decision‑support patterns under time pressure. - Clear prioritization and crisp trade‑off reasoning aligned to latency, reliability, and safety. - Quant/metric fluency and a pragmatic experimentation plan. - Communication that’s concise, structured, and calm under pushback. Artifacts you may produce live: user/task flows; IA; box‑and‑arrow wireframes for Overview, Blotter, Alerts, What‑If; state diagrams for error/degradation; metric tree. Common follow‑ups: adapting for global desks and mobile incident response; accessibility in dark, high‑glare environments; localization/time‑zone handling; keyboard maps and undo/confirm patterns for irreversible actions.