Senior C# Engineer - Execution & Portfolio Systems - Trading Application - Multi Billion Dollar Multi-Strat - Up to £400k TC

Senior C# Engineer - Execution & Portfolio Systems - Trading Applications - Multi Billion Dollar Multi-Strat - Up to £400k TC

A leading global investment firm is hiring a Senior Software Engineer to join its front-office engineering group in London, building the core applications used by portfolio managers, traders, and risk analysts to run the business day to day.

This is a hands-on engineering role, not a platform or infrastructure seat. The work is greenfield application development; designing and building the tools that sit directly in front of investment professionals and underpin live portfolio management, order workflow, position modelling, and capital allocation decisions.

The Role

You will own significant pieces of the application stack, working directly alongside PMs and traders to understand what they need and build it. Typical work includes:

Portfolio management and order raising platforms, intra-day position and P&L modelling, FX hedge modelling with live pricing, trade lifecycle and order blotter systems, multi-model orchestration and analytics platforms, front-office workflow tooling and internal applications, and modernisation of legacy Excel and VBA systems into production-grade .NET applications.

This is a building role. The expectation is that engineers take full ownership from requirements through architecture through delivery and operate as genuine partners to the investment teams they support.

The Environment

The engineering culture is small, senior, and highly autonomous. Engineers are expected to gather requirements directly from stakeholders, make architectural decisions independently, and deliver without heavy process overhead. The strongest performers here are commercially curious, technically rigorous, and enjoy understanding the business impact behind what they build.

The firm values engineers who can move between greenfield builds, complex integrations, and modernisation work without losing velocity.

What They're Looking For

Deep production C# and .NET engineering experience, ideally within front-office environments at hedge funds, asset managers, or investment banks. Experience building portfolio management, order management, or investment workflow applications. Strong understanding of system architecture, data modelling, and high-throughput application design. Engineers who take initiative, communicate confidently with non-technical stakeholders, and care about what they ship.

A background in financial markets; P&L, position management, and execution workflows is a meaningful advantage.

What Makes Someone Successful Here

The engineers who thrive tend to have built things that front-office users depend on in live environments. They understand the difference between what a PM asks for and what they actually need. They're comfortable owning a problem end to end and aren't waiting for someone else to define the architecture.

Interview Process

Recruiter screen → Technical assessment (C#) → Hiring manager interview → Final onsite with engineering and investment stakeholders