Design real-time stock price viewer

Q: Design real-time stock price viewer

This question evaluates system-design competency in building low-latency, high-throughput real-time streaming systems, covering ingestion, normalization, deduplication, aggregation, pub/sub dissemination, and operational resilience.

Q: How do I approach System Design interview questions?

System Design questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master system design interviews.

Q: What difficulty level is this interview question?

This is a hard difficulty System Design question, commonly asked during Onsite rounds at Coinbase.

Q: What role is this question designed for?

This question is commonly asked for Software Engineer candidates at Coinbase during technical interviews.

Question

System Design: Real‑Time Stock Prices Viewer (No History)

You are designing a real‑time system that lets clients view current stock prices only. No historical queries are supported.

Assume:

Real‑time view of last trade price and top‑of‑book (best bid/ask) per symbol.
Multiple upstream market feeds (e.g., SIP and/or direct exchange feeds).
Millions of concurrent end users with watchlists.

Describe and justify a design that covers:

Ingestion and Processing
- Ingesting market data feeds (parsing, sequencing, network considerations).
- Symbol normalization and reference data management.
- Deduplication and out‑of‑order handling.
- Aggregation (per‑venue books, cross‑venue top‑of‑book, last trade).
Client Dissemination
- Transport and pub/sub choices (e.g., WebSockets vs. SSE vs. long polling).
- Fan‑out strategy and edge distribution.
- Caching current values for fast snapshots.
API and Controls
- API design for initial snapshot and live updates.
- Throttling and quotas (per connection, per symbol, message rates).
Performance and Reliability Goals
- Latency and consistency targets.
- Backpressure policy and delivery semantics to clients.
- Horizontal scaling to millions of concurrent users.
Resilience and Operations
- Fault tolerance, failover, and multi‑region active/active deployment.
- Monitoring, alerting, and on‑call runbooks.
- Testing strategies (including load tests and simulators).

Keep the scope to real‑time only (no historical query capabilities). State reasonable assumptions where needed and explain trade‑offs.

Design real-time stock price viewer

Quick Overview

Design real-time stock price viewer

System Design: Real‑Time Stock Prices Viewer (No History)

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