Fanatics·Software Engineer·Onsite - System Design / Architecture
Jun 2026
System design round at Fanatics for a software engineer role. The whole thing was basically one massive question about building a Robinhood-style trading platform, and they really did mean the whole thing, from KYC onboarding all the way to options extensibility.
- Design an online retail stock trading platform similar to Robinhood. Walk through the full system: user onboarding with identity verification and funding via bank transfer, real-time balances, market data ingestion and streaming quotes, order lifecycle including validation, risk checks, and idempotency, routing to exchanges or market makers, post-trade clearing, portfolio and positions with cost basis and P&L, and how you'd handle corporate actions.
- How would you handle the data model and storage strategy for orders, trades, account state, and market tick data? What are the consistency and latency tradeoffs between order state and portfolio views?
- How would you decompose this system into services, and where would you use synchronous APIs versus asynchronous messaging? Describe your use of message queues and event sourcing.
- How do you design for scale and reliability during market open surges? What failure modes worry you most, and how do you handle a market data outage?
- What observability, compliance logging, and auditing would you build into this system? How would you handle incident response for a production failure?
- How would you extend this design later to support options trading or cryptocurrency?
“This is a monster of a question.”