Senior Software Engineer - C# - £150 - 180k

A rare opportunity to join a highly successful quantitative investment fund as a Senior Software Engineer, working at the heart of a technology-driven trading environment. Our client is a highly respected quantitative investment firm with a strong track record and a technology-first culture. They are now looking to hire an exceptional Senior Software Engineer with strong C#/.NET experience to join their growing engineering team in London. This is a particularly interesting opportunity for an engineer who wants to move beyond traditional software development and work on complex, high-performance systems where technology has a direct impact on investment performance. You'll work alongside experienced software engineers, quantitative researchers and other technical specialists, solving challenging problems across performance, scalability, data and distributed systems. As a Senior Software Engineer, you'll take ownership of the design and development of critical systems supporting the firm's quantitative investment strategies. You'll be involved across the full engineering lifecycle — from understanding the problem and shaping the architecture, through to implementation, optimisation and production. Your responsibilities will include:

• Designing and developing high-performance C#/.NET systems
• Building scalable applications and services used by quantitative and investment teams
• Working closely with quantitative researchers to translate complex ideas into robust production software
• Designing systems capable of processing significant volumes of data
• Investigating and resolving complex performance and scalability challenges
• Applying modern software engineering principles to build highly reliable systems
• Contributing to architectural and technology decisions
• Improving engineering standards, development practices and tooling
• Mentoring less experienced engineers and helping shape the technical direction of the team We're looking for a strong software engineer who enjoys working on technically demanding problems and has developed significant expertise in C# and .NET. You'll ideally have:
• Extensive commercial experience with C# and .NET
• Strong understanding of modern C#, including concurrency, asynchronous programming and performance optimisation
• Excellent knowledge of algorithms, data structures and software design
• Experience designing and developing complex, production-grade systems
• Strong understanding of distributed systems and scalable architectures
• Experience working with databases and high-volume data
• A strong focus on code quality, testing and maintainability
• Experience diagnosing and optimising performance-critical applications
• Excellent problem-solving and communication skills Experience within quantitative finance, trading, financial markets, low-latency systems or high-performance computing would be advantageous, although our client is also very interested in engineers coming from other technically demanding environments. The technology The core technology stack is C#/.NET, supported by a modern engineering environment. Depending on your area of focus, you may work with technologies including: C# - .NET - SQL - Linux - Azure - Docker - Kubernetes - Kafka - Distributed Systems - CI/CD ·