Job Description

Position Overview
CITIGROUP is one of the largest players in the financial industry, employing more than 200,000 people across the globe.
In the UK, CITI is a major employer with over 6000 people in London.
The Commodities Index business at CITI has grown significantly in the last 10 years to become one of the leading industry players. It is a federated business model that covers market making across all types of assets including Oil, Gas, Power, Agriculture, Metals etc.
This role is within the London Commodities Index Technology team, focussing on rolling out a new Index back-testing tool for Commodities structuring team.
We are seeking an experienced and highly motivated Python Developer to join our Commodities Index business on a contract basis. The successful candidate will play a critical role in build and deploying robust, scalable and high-performance systems for back-testing index modes, generating weights, pricing indices and decomposing complex commodities baskets.
You will work closely with business and front office, contributing to the development of advanced tools and services that power our index products and analytical frameworks.
We are committed to hiring the brightest and best technical experts and in return can offer roles with direct business interaction and day-to-day usage of the latest technology.
Key Responsibilities

• Design, develop and optimize Python-based Index calculators platform for decomposition and attribution analytics
• Develop high-performance, scalable APIs using Flask or FastAPI for internal and client-facing tools
• Work directly with front office and business to gather requirements and iterate rapidly on deliverables.
• Implement robust testing, versioning and data validation mechanisms
• Maintain clean, well-documented and modular code with a focus on performance and reliability.
• Ensure seamless integration with internal data sources, storage systems and reporting tools.

Required skills and Experience:

• Proven Python development experience, preferably in financial services or commodities trading environments.
• Strong expertise in Pandas, NumPy and other scientific computing libraries
• Proven experience with FastAPI or Flask for API development
• Deep understanding of time-series data manipulation and back-testing frameworks
• Experience working with large data sets and real-time data pipelines
• Strong debugging and profiling, and performance optimization skills
• Excellent communication skills and ability to interact effectively with non-technical stakeholders (strafing and structuring teams)

• Strong problem-solving skills and ability to troubleshoot complex Python-related issues.

Preferred Skills

• Previous experience with commodities indices, structured products or financial index engineering
• Familiarity with market data platforms and pricing feeds (e.g., Bloomberg, Refinitiv etc)
• Exposure to containerization (Docker) and Cloud platforms (AWS, GCP etc)
• Knowledge of database systems (SQL/NoSQL) and data serialization formats (Parquet/HDF5 etc)

Why Join Us

• Work on cutting-edge financial products with a direct impact on the business
• Collaborate with top-tier professionals in front office and business
• Opportunity to build greenfield tools and systems in a dynamic environment
• Fast Iteration and Deployment: Lean team structure means fast feedback loops, quicker decision-making and visible outcomes from your work
• High Visibility and Impact: You work will support mission-critical processes and contribute directly to P&L and client-facing deliverables

This job description provides a high-level review of the types of work performed. Other job-related duties may be assigned as required.
What we'll provide you
By joining Citi London, you will not only be part of a business casual workplace with a hybrid working model (up to 2 days working at home per week), but also receive a competitive base salary (which is annually reviewed), and enjoy a whole host of additional benefits such as:

• 27 days annual leave (plus bank holidays)
• A discretional annual performance related bonus
• Private Medical Care & Life Insurance
• Employee Assistance Program
• Pension Plan
• Paid Parental Leave
• Special discounts for employees, family, and friends
• Access to an array of learning and development resources

Alongside these benefits Citi is committed to ensuring our workplace is where everyone feels comfortable coming to work as their whole self, every day. We want the best talent around the world to be energized to join us, motivated to stay and empowered to thrive.
#LI-AP2
Job Family Group: Technology
Job Family: Applications Development
Time Type: Full time
Most Relevant Skills Please see the requirements listed above.
Other Relevant Skills For complementary skills, please see above and/or contact the recruiter.
Citi is an equal opportunity employer, and qualified candidates will receive consideration without regard to their race, color, religion, sex, sexual orientation, gender identity, national origin, disability, status as a protected veteran, or any other characteristic protected by law.
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