Design market price change notifications

Design a real-time alerting service that notifies users when the market price of a symbol in their watchlist changes. Context and requirements: Each user maintains a personal set of tracked ticker symbols, such as AAPL or TSLA. A third-party market data provider is available and supports both REST-based polling and WebSocket streaming. The system should deliver near-real-time price-change alerts to users through channels such as mobile push, email, or in-app WebSocket…