Quantitative Developer in London

Why work for us? A career at Janus Henderson is more than a job, it’s about investing in a brighter future together. Our Mission at Janus Henderson is to help clients define and achieve superior financial outcomes through differentiated insights, disciplined investments, and world-class service. We will do this by protecting and growing our core business, amplifying our strengths and diversifying where we have the right.

Our Values are key to driving our success, and are at the heart of everything we do:

• Clients Come First - Always
• Execution Supersedes Intention
• Together We Win
• Diversity Improves Results
• Truth Builds Trust

If our mission, values, and purpose align with your own, we would love to hear from you!

Your opportunity:

• Partner with asset allocation PMs and researchers to take ideas from notebook to production: signals, CMAs, optimization, portfolio construction, rebalancing rules, and attribution.
• Build and extend the team's research platform: data ingestion, back testing, scenario analysis, portfolio construction, monitoring, and reporting.
• Own the multi-asset data layer: market data, macro, fundamentals, fund and index data, internal holdings, with quality control the PMs actually trust.
• Use AI coding agents daily for prototyping, refactoring, testing, review, and documentation. Bring opinions on where they help and where they hurt.
• Build internal AI-backed tooling for the team where it earns its keep: research workflows, client-reporting drafts, commentary support, meeting prep.
• Write production code that other quants want to build on. Own reliability, testing, and observability for what you ship.
• Mentor teammates on effective AI-augmented engineering practice.
• Carry out other duties as assigned.

What to expect when you join our firm:

• Hybrid working and reasonable accommodations.
• Generous Holiday policies.
• Excellent Health and Wellbeing benefits including corporate membership to ClassPass.
• Paid volunteer time to step away from your desk and into the community.
• Support to grow through professional development courses, tuition/qualification reimbursement and more.
• Maternal/paternal leave benefits and family services.
• Complimentary subscription to Headspace – the mindfulness app.
• All employee events including networking opportunities and social activities.
• Lunch allowance for use within our subsidized onsite canteen.

Must have skills:

• Have built industrial-scale enterprise-quality quantitative/systematic models based on specs provided by PM's.
• Have deployed quantitative/systematic models to production at non-trivial size.
• Have monitored operational performance of these models and taken ownership of making sure the models behave properly.
• Are familiar with the SDLC (e.g. testing/deployment).
• Are heavy users of modern AI tools (claude code/codex/opencode/pi/ampcode/factory droid/cursor/cline).
• Have written extensive documentation about the implementation of a model.

Nice to have skills:

• Working knowledge of financial markets preferred.
• Knowledge of Excel preferred.
• Github (or other version control), CI/CD and/or cloud services experience is beneficial.
• Excellent interpersonal, relationship building and customer service skills.
• Strong econometrics and statistics background, experience in asset pricing empirical work.
• Passionate about financial markets with a curiosity about investing.

Supervisory responsibilities: No.

Potential for growth:

• Mentoring.
• Leadership development programs.
• Regular training.
• Career development services.
• Continuing education courses.

You will be expected to understand the regulatory obligations of the firm, and abide by the regulated entity requirements and JHI policies applicable for your role.

We are happy to be asked about work flexibility and our hybrid working environment. If you need any reasonable accommodations during our recruitment process, please let us know.

Annual Bonus Opportunity: Position may be eligible to receive an annual discretionary bonus award from the profit pool. The profit pool is funded based on Company profits. Individual bonuses are determined based on Company, department, team and individual performance.

Benefits: Janus Henderson is committed to offering a comprehensive total rewards package to eligible employees that includes competitive compensation, pension/retirement plans, and various health, wellbeing and lifestyle benefits.

The company is an equal opportunity employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, disability or veteran status. All applications are subject to background checks.

Janus Henderson (including its subsidiaries) will not maintain existing or sponsor new industry registrations or licenses where not supported by an employee’s job functions (as determined by Janus Henderson at its sole discretion).

You should be willing to adhere to the provisions of our Investment Advisory Code of Ethics related to personal securities activities and other disclosure and certification requirements, including past political contributions and political activities. Applicants’ past political contributions or activity may impact applicants’ eligibility for this position.