Sr Lead Software Engineer(Python/AWS/SQL)

## ROLE SUMMARY

Are you a hands-on engineer who raises the bar for everyone around you?

Join us at FTSE Russell! We're establishing a team of engineers passionate about software craftsmanship, quality, and substantial impact. As a Lead Software Engineer, you'll own the technical direction of the software that powers the indices trusted by financial institutions worldwide.

We build primarily in Python, so that's our preference - but depth of engineering judgement matters more to us than the language on your CV. If you've led the design and delivery of serious systems in Java, C#, C, C++, Scala, Go, or Rust and you're motivated to lead in Python, we'd like to talk. At this level we expect you to become fluent quickly and to bring the cross-language perspective with you.

This is a hands-on Lead IC role - not a management role. You'll still be writing and reviewing code every week. What changes at this level is scope: you own architecture and technical direction in a defined area, you mentor and grow the engineers around you, and you raise quality across the team through reuse, good design, and hands-on support. The systems handle serious volumes of financial data, so there's real depth in the data problems - but you're being hired as a software engineer who leads through code.

If you're excited about building systems that matter and making the engineers around you better, we'd love to meet you.

## WHAT YOU'LL BE DOING

We're building the next-generation index data platform at FTSE Russell - and we want you to shape it with us:

- Staying hands-on - designing and writing production code, primarily in Python with 10 +yrs of experience , and setting the standard for what good looks like through the code you ship

- Owning technical direction and architecture for a defined area of the platform, and making the trade-offs explicit so the team can move fast with confidence

- Leading design of software systems - services, APIs, shared libraries, and the interfaces between them - with resilience, performance, and reusability designed in

- Driving engineering quality across the team: raising the bar in code review, reducing duplication through well-designed shared components, and championing testing, refactoring, and secure development practices

- Mentoring and coaching engineers - pairing, reviewing, and growing capability so that good practice outlives any one project

- Digging into design and risk trade-offs - failure modes, operational readiness, security, and cost - and resolving the blockers that slow the team down

- Designing data-intensive software across relational databases (Aurora PostgreSQL), object storage, and AWS services, with careful attention to schema design and evolution at scale

- Building software that processes data at scale on AWS - Lambda, containerised services, and where appropriate Glue, EMR Serverless, and lakehouse table formats such as Apache Iceberg

- Embedding observability and quality controls so issues are found before customers find them

- Influencing and collaborating across teams, and translating between technical and non-technical audiences

- Building deep knowledge of the financial indices domain and using it to guide team-level design

## WHAT YOU'LL BRING

Essential - this is the bar:

- A substantial track record of building and shipping software. Applications, services, platforms, or libraries you designed, built, ran in production, and evolved over years - not just pipelines and scripts

- Python is our preference, but not a hard gate at this level either. Either you already lead in production Python, or you have equivalent depth in Java, C#, C, C++, Scala, Go, or Rust and are motivated to make Python your primary language here. Engineers who have worked across several languages often bring the sharpest design judgement, and we value that

- Depth in software design and architecture - you can decompose a complex problem, choose the right boundaries, and explain why. You know which patterns earn their keep and which are cargo cult

- You write and review excellent code. In Python: type hints, linters, strong pytest discipline, and an instinct for readable, maintainable code - and the equivalent rigour in any other language you've worked in

- You are genuinely hands-on and intend to stay that way. Leading through code is the point of this role

- Proven experience mentoring and levelling up other engineers - through code review, pairing, design guidance, and setting standards

- Strong ownership of technical outcomes - you take responsibility for what production does, not just what merges

- Deep experience with relational databases (e.g. Aurora PostgreSQL) - modelling, performance, and evolution under real load

- Solid AWS experience and strong CI/CD, automation, and testing practice

- Comfort with data-intensive systems - batch processing, ETL, schema evolution, and reasoning about correctness at volume

- Excellent communication - you tailor how you explain design decisions to technical and non-technical audiences and create shared understanding

- You value collaboration over solo heroics and thrive in Agile teams

## NICE TO HAVES

Beneficial, but not what we're screening on:

- Apache Spark / PySpark and experience optimising large-scale distributed processing

- Big data experience - designing systems for datasets and workloads well beyond single-machine scale

- Breadth across languages used in data-intensive and performance-critical systems - Scala, Java, C++, Go, or Rust - and the judgement to know when reaching for one is warranted

- Apache Iceberg, Delta Lake, or similar open table formats, and lakehouse architecture

- Databricks, Snowflake, or comparable data platforms

- CI/CD tooling such as GitLab CI, Jenkins, or GitHub Actions

- Infrastructure as code (Terraform, CDK) and platform/DevOps exposure

- Data quality frameworks like Great Expectations or Deequ

- Experience in financial markets, index data, or investment analytics

- Experience in finance domain (investment banking, asset/portfolio management) or in any product company

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Join us and be part of a team that values innovation, quality, and continuous improvement. If you're ready to take your career to the next level and make a significant impact, we'd love to hear from you.

Career Stage:

London Stock Exchange Group (LSEG) Information:

Join us and be part of a team that values innovation, quality, and continuous improvement. If you're ready to take your career to the next level and make a significant impact, we'd love to hear from you.

LSEG is a leading global financial markets infrastructure and data provider. Our purpose is driving financial stability, empowering economies and enabling customers to create sustainable growth.

Our purpose is the foundation on which our culture is built. Our values of Integrity, Partnership, Excellence and Change underpin our purpose and set the standard for everything we do, every day. They go to the heart of who we are and guide our decision making and everyday actions.

Working with us means that you will be part of a dynamic organisation of 25,000 people across 65 countries. However, we will value your individuality and enable you to bring your true self to work so you can help enrich our diverse workforce.

We are proud to be an equal opportunities employer. This means that we do not discriminate on the basis of anyone’s race, religion, colour, national origin, gender, sexual orientation, gender identity, gender expression, age, marital status, veteran status, pregnancy or disability, or any other basis protected under applicable law. Conforming with applicable law, we can reasonably accommodate applicants' and employees' religious practices and beliefs, as well as mental health or physical disability needs.

You will be part of a collaborative and creative culture where we encourage new ideas. We are committed to sustainability across our global business and we are proud to partner with our customers to help them meet their sustainability objectives. Our charity, the LSEG Foundation provides charitable grants to community groups that help people access economic opportunities and build a secure future with financial independence. Colleagues can get involved through fundraising and volunteering.

LSEG offers a range of tailored benefits and support, including healthcare, retirement planning, paid volunteering days and wellbeing initiatives.

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