End-to-End Design
Design a retail stock-trading app: users watch live prices for the symbols they follow, place buy and sell orders, and see their cash and share balances change as those orders execute.
In scope: streaming live quotes, placing and tracking market and limit orders, and maintaining cash balances and share positions as orders fill. Out of scope: the exchange's own matching-engine internals, options/crypto/margin trading, the trading UI itself, market-data provider integration specifics, and clearing/settlement (the process that finalizes money and share transfers the following business day).
What a strong answer sounds like
State the decision, connect it to a requirement, and name the tradeoff. Keep the design focused on the workload in the prompt.
The AI interviewer asks about this part of Design Robinhood (Stock Trading). The interviewer guides you through topics one by one.