Mock system design interview at Bloomberg
A live 45-minute round on a question reported in Bloomberg interviews, run by an AI interviewer that asks one thing at a time, probes what you say, looks at your whiteboard, and weighs what that round is reported to weigh. It ends with a debrief: a score, what was strong, what was missing.
Design a Stock Exchange
Match buy and sell orders in microseconds, in a strict and provable order, never lose a fill, and stay correct when the matching engine dies mid-trade.
You will not see the requirements, the numbers or the design before you start. That is the point.
What the Bloomberg round is reported to look like
45–60 minutes, often on real-time financial data close to what Bloomberg runs: price updates fanned out to Terminal users, low-latency messaging, alerting or news pipelines. Some teams instead show their own architecture and ask how you would improve it.
What it weighs
- Low latency and high throughput on data that changes constantly
- Fan-out of live updates to a very large number of subscribers
- Choices that survive persistent follow-ups: why this one, what fails first, what you rejected
- On existing-system prompts: questions about the setup and its goals before any change
The common mistake
Bringing a generic template. Prompts are reported to sit close to real, latency-sensitive systems and interviewers keep pulling on each choice, so ask about the actual setup and constraints first and propose only what you can defend.
From public interview guides and candidate reports, and Bloomberg’s own interview guidance where it publishes any. Not endorsed by Bloomberg. The interviewer is an AI running in that style; it is practice, not a prediction.
Start the round
The interviewer’s opening question is free. Answering it is part of Pro. See an example round and its debrief →
The 3 questions this round draws from
Each is reported in Bloomberg interviews. Pick one to sit, or read its reference design and walk through a strong answer first.
- Design a Stock ExchangeMatch buy and sell orders in microseconds, in a strict and provable order, never lose a fill, and stay correct when the matching engine dies mid-trade.drawn
- Design a Real-Time LeaderboardRank 300 M players of a mobile game in real time: the global top 100, your exact rank among millions, your friends, and daily, weekly and season boards that reset on time.
- Design RobinhoodA retail brokerage: live prices to 3 M phones, 20 k orders a second at the open, every share and cent exact.
Other companies: Anthropic · Google · Meta · Amazon · OpenAI · Microsoft · Uber · DoorDash