C# SQL Developer Performance & Optimisation

About Phi Partners

Phi Partners has been a trusted capital markets consultancy for more than 20 years, providing quantitative and technology expertise across front office, pricing and risk. We support more than 80 financial institutions across the buy-side and sell-side through niche capabilities spanning quant, engineering, vendor platforms and cloud infrastructure. Our teams work on complex, real-world problems across models, analytics, applications, data and cloud infrastructure, within an international delivery organisation built around regional hubs and specialist centres of excellence. For people who enjoy technically demanding work in capital markets, Phi offers the opportunity to work closely with expert colleagues and major financial institutions on high-value, business-critical initiatives.

About the Programme

One of our clients is a leading European corporate and investment bank with a substantial global markets franchise, operating across front-office, risk and post-trade technology from its Paris technology hub.

Phi Partners is supporting the bank's trade and sensitivities repository team, within the risk IT function of its Global Markets & Risks division. The team delivers regulatory, business and architecture change projects, evolves and maintains the business information system, and provides daily support to Risk, Results, Front Office and Back Office users.

The mission centres on an application that assigns a payoff identifier (financial instrument type) and an observability level (Fair Value Level) to each instrument, based on its characteristics and business mapping rules. It processes very large volumes of data, instruments, trades, assets, positions, sensitivities, stress shocks and XVA, from multiple sources. The objective is to analyse, optimise and rework the determination algorithm to reduce batch processing time.

Role and Responsibilities

We are looking for a senior C# / SQL developer with a strong performance and optimisation focus to take ownership of the batch processing behind this application. You will be :

• Analysing payoff and observability determination algorithms, reviewing processing logic, calculation flows and data dependencies to identify functional and technical inefficiencies
• Reengineering core algorithms and SQL queries, simplifying processing logic and improving data retrieval and transformation across the application
• Profiling C# application components and Oracle database operations, diagnosing execution bottlenecks and optimising resource-intensive processes across high-volume datasets
• Managing batch processing workflows through Control-M, supporting the C#/Oracle batch application and ensuring reliable scheduling, execution and integration with downstream processes
• Working with Big Data processing on Hadoop, analysing large-scale data workflows and contributing to improvements across distributed batch-processing components
• Supporting the Angular/NestJS web interface, investigating application behaviour and ensuring effective integration between the frontend, backend services and underlying processing components
• Identifying architectural and technical improvements, independently evaluating existing implementations, proposing solutions and driving changes from development through production delivery
• Documenting technical implementations and validating application changes, performing functional and regression testing to safeguard business logic, data integrity and system reliability

Key Skills

The ideal candidate will have:

• Demonstrating strong C#/.NET and Oracle SQL engineering expertise, with a proven focus on building robust, efficient and high-performing applications.
• Applying proven performance engineering techniques, including batch runtime optimisation, SQL and index tuning, and profiling of CPU and memory utilisation to identify and resolve bottlenecks.
• Designing, developing and supporting large-scale batch processing solutions, with practical experience working with scheduled workloads and Control-M orchestration.
• Working with high-volume data processing technologies, including Hadoop and Big Data ecosystems, with exposure to Spark, Scala, Python, Hive and Kafka.
• Developing and supporting modern web applications, with experience across Angular and NestJS and their integration with backend processing services.
• Working autonomously on complex technical challenges, taking ownership of analysis, solution design, implementation and resolution from initial investigation through delivery.
• Demonstrating strong senior-level engineering and problem-solving capabilities, proactively identifying opportunities for technical improvement and delivering pragmatic, scalable solutions.
• Fluent English communication.
• Desirable : Applying knowledge of capital markets and financial technology environments, with an understanding of standard financial products, valuation processes, risk management and trade repository platforms

Next steps

This is an opportunity to work on genuinely low-latency, high-throughput components at the centre of an electronic trading platform, in a team with real ownership of its technology. If you are interested in this role, please email me your CV at [email protected] along with your availability for a call so that we can discuss it further.