Quantitative Developer in London

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.

Required 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, monitored their operational performance, and taken ownership of ensuring proper behavior.
• Are familiar with the SDLC (e.g., testing/deployment).
• Are heavy users of modern AI tools (Claude Code/Codex/OpenCode/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.

Leadership and Development

• Supervisory responsibilities: None.
• Potential for growth.
• Mentoring.
• Leadership development programs.
• Regular training.
• Career development services.
• Continuing education courses.

Regulatory and Ethical Requirements

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.

EEO Statement

Janus Henderson Investors 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.

Legal and Code of Ethics

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.