The Firm

XTX Markets is a leading algorithmic trading firm which uses state-of-the-art machine learning technology to produce price forecasts for over 50,000 financial instruments across equities, fixed income, currencies, commodities and crypto. It uses those forecasts to trade on exchanges and alternative trading venues, and to offer differentiated liquidity directly to clients worldwide. The firm trades over $250bn a day across 35 countries and has over 250 employees based in London, Singapore, New York, Paris, Bristol, Mumbai, Yerevan and Kajaani.

We leverage the talent of the people who work here, modern computational techniques and state-of-the-art research infrastructure to analyse large data sets across markets quickly and efficiently, to maximize the effectiveness of our proprietary trading algorithms. We are actively seeking new methods and ideas. The models that drive our trading strategies have evolved considerably over the last 10 years, from econometric methods that gave our company its name, to trees, to neural networks, to modern deep learning architectures.

XTX Markets has an unrivalled level of computational resources in the trading industry, with a growing research cluster currently containing over 25,000 GPUs with 650 petabytes of usable storage. Teams across the firm include world-class researchers, developers and technologists with backgrounds in pure math, programming, physics, computer science and machine learning. The firm is also constructing a large-scale data centre in Finland to future-proof its significant computational capabilities.

At XTX Markets technology is our business and we are a diverse organization which attracts outstanding talent from across all industry backgrounds. We are focused on teamwork, and our people collaborate on all aspects of the business, working openly and with respect for each other, our clients and the market. Our culture is non-hierarchical and one where everyone is valued. We strive for excellence in everything we do.

The Role

The Trading Data Technology is a new team at XTX Markets: it is responsible for the design, implementation, and operation of the firm’s Trading Data platform. The platform is an early stage / greenfield build. Its initial projects will be centred around standardising the capture of the firm's order data, as well as how we make it available to systems and users.

This system is designed to be highly available, handling hundreds of millions of messages a day in real time. There will also be multiple forms of storage to support the platform’s various stakeholders, including kafka, column-store databases, and S3-like files.

Developers at XTX are engaged in the entire software development lifecycle of software development. Developers work closely with other teams to gather requirements, before implementing, delivering and supporting their solutions. The Trading Data Technology team will be based in London. However, stakeholders to the platform exist in multiple locations including London, New York & Singapore.

There is currently a shared support rota with the Post Trade Technology team, which includes weekend on call every 10 weeks.

Responsibilities

• Back-end services are built in Go with some additional web-based GUI development in React. Engineers at XTX adopt a tech agnostic approach, opting for the best tool for each specific task. We do not expect candidates to have prior experience in front-end programming, or Golang, but it is essential that you are open-minded to using new technologies as appropriate.
• Communicate across front and back-office teams and users of the platform to understand wider business requirements and convert them into scalable, technical solutions.
• There is currently a shared support rota with the Post Trade Technology team, which includes weekend on call every 10 weeks.
• This is the 2^nd hire for the team, and the hire will be expected to own the design and development for their projects.

Essential Attributes

• A solid grounding in academic CS fundamentals, algorithms and data structures. Demonstrated commitment to rigorous software engineering discipline.
• Strong proficiency in a statically typed language. Prior experience with Golang is desirable, but certainly not required. Similarly, experience with front-end programming is not required.
• Desire to take ownership over projects and complex technical challenges.
• Familiarity with concurrent programming techniques and exposure to asynchronous, distributed systems.
• Understand database performance characteristics including indexing, query execution, with experience designing and optimising schemas and queries.
• Finance experience is not required, but the role will rapidly entail becoming a subject matter expert in the domain.
• We are targeting approximately 3 to 5 years’ experience. We view applications holistically and do have some flexibility around exact experience level. Please note that, whilst this role will involve significant ownership over projects; it is likely not suitable for those targeting a leadership position.

Benefits

• Onsite gym, sauna, and fitness classes at no charge.
• Extensive medical benefits including an on-site doctor and therapist at no charge.
• Breakfast and lunch provided daily.
• Various supports for caregivers, including emergency dependent care.
• Beautiful Kings Cross office: https://vimeo.com/257888726
• 25 days paid holiday per year + statutory holiday and paid sick days. We currently operate 4 days a week in-office, 1 from home.

We are looking for an experienced lawyer to join us as Legal Counsel. The role will report to the Legal Director and be part of a global legal team supporting a fast-growing, market-leading company. You will collaborate closely with a team of experienced commercial lawyers across multiple regions, sharing knowledge and contributing to a high-performing, business-oriented legal function, while helping scale and refine processes to support continued growth. The ideal candidate has a sharp business focus, is proactive, decisive, and highly collaborative. Your primary responsibility will be to lead and support the company’s commercial activities end-to-end, with a strong focus on both sales (revenue-generating) and procurement (vendor and partner) engagements. You will act as a proactive business partner, taking ownership of transactions from initial structuring through negotiation and execution. This includes anticipating legal and commercial risks, driving alignment across stakeholders, and helping move deals forward efficiently. You are expected to lead deals—not just support them—and play a key role in enabling the business to move quickly and responsibly.

Responsibilities:
·       Provide practical, business-oriented legal advice and actively support company departments (Sales, Product, Operations, Marketing, HR, etc.) in addressing a wide variety of legal and commercial matters
·      Structure, draft, and lead the negotiation of complex agreements, while effectively engaging with sales professionals, internal stakeholders, and representatives of customers and partners across APAC and EMEA
·      Apply and leverage expertise across a broad range of technology agreements, including sales, licensing, consulting, services, OEM, vendor, NDA, open-source, channel partner, and strategic alliance agreements
·      Proactively monitor and guide the business on data privacy and other applicable laws and regulations
·      Develop, implement, and continuously improve standard templates, business processes, and internal policies to support scalable growth

Requirements
·      Law degree (Juris Doctor / LL.B or equivalent) and admission to at least one bar
·      5-7+ years of experience in commercial law from global high-tech companies and private practice (advising international clients)
·      Strong background from the technology, data, and security industries
·      High capability of independently, effectively, and proactively negotiate various commercial agreements whilst partnering with internal and external stakeholders
·      Relevant experience negotiating and finalizing Software-as-a-Service (SaaS) agreements as well as software licenses agreements with large enterprise customers, value-added resellers, agents, distributors, vendors and technology partners
·      Knowledge and understanding of privacy and data protection laws and regulations
·      Fluent in English (written and spoken)
·      Candidate must possess strong communication, analytical and organizational skills with an attention to complex detail
·      Experience working in a cross functional global organization is required
·      Ability to multi-task in a dynamic and fast-paced work environment
·      Outstanding interpersonal skills

Are you a medical doctor eager to shape the future of AI? Large-scale language models are evolving from clever chatbots into powerful engines of scientific discovery. With high-quality training data, tomorrow’s AI can democratize world-class education, keep pace with cutting-edge research, and streamline clinical work for healthcare professionals everywhere. That training data begins with you—we need your expertise to help power the next generation of AI.

We’re looking for medical professionals who live and breathe internal medicine, pharmacology, pathology, clinical diagnostics, medical ethics, human physiology, epidemiology, immunology, and evidence-based medicine. You’ll challenge advanced language models on topics like differential diagnosis, drug interactions, treatment protocols, pathophysiological mechanisms, clinical trial design, public health interventions, and diagnostic imaging interpretation—documenting every failure mode so we can harden model reasoning.

On a typical day, you will converse with the model on clinical scenarios and theoretical medical questions, verify factual accuracy and logical soundness, capture reproducible error traces, and suggest improvements to our prompt engineering and evaluation metrics.

An MD or DO is required for this role. Clear, metacognitive communication—explicitly articulating reasoning and decision processes “showing your work”— is essential.

Ready to turn your medical expertise into the knowledge base for tomorrow’s AI? Apply today and start teaching the model that will teach the world.

We offer a pay range of $40 - $120 per hour, with the exact rate determined after evaluating your experience, expertise, and geographic location. Final offer amounts may vary from the pay range listed above. As a contractor you’ll supply a secure computer and high-speed internet; company-sponsored benefits such as health insurance and PTO do not apply.

Job title: Medical Specialist – AI Trainer
Employment type: Contract
Workplace type: Remote
Seniority level: Senior Level

The Firm

XTX Markets is a leading algorithmic trading firm which uses state-of-the-art machine learning technology to produce price forecasts for over 50,000 financial instruments across equities, fixed income, currencies, commodities and crypto. It uses those forecasts to trade on exchanges and alternative trading venues, and to offer differentiated liquidity directly to clients worldwide. The firm trades over $250bn a day across 35 countries and has over 250 employees based in London, Singapore, New York, Paris, Bristol, Mumbai, Yerevan and Kajaani.

We leverage the talent of the people who work here, modern computational techniques and state-of-the-art research infrastructure to analyse large data sets across markets quickly and efficiently, to maximize the effectiveness of our proprietary trading algorithms. We are actively seeking new methods and ideas. The models that drive our trading strategies have evolved considerably over the last 10 years, from econometric methods that gave our company its name, to trees, to neural networks, to modern deep learning architectures.

XTX Markets has an unrivalled level of computational resources in the trading industry, with a growing research cluster currently containing over 25,000 GPUs with 650 petabytes of usable storage. Teams across the firm include world-class researchers, developers and technologists with backgrounds in pure math, programming, physics, computer science and machine learning. The firm is also constructing a large-scale data centre in Finland to future-proof its significant computational capabilities.

At XTX Markets technology is our business and we are a diverse organization which attracts outstanding talent from across all industry backgrounds. We are focused on teamwork and our people collaborate on all aspects of the business, working openly and with respect for each other, our clients and the market. Our culture is non-hierarchical and one where everyone is valued. We strive for excellence in everything we do.

The Role

XTX is a research-driven organisation, built and led by passionate mathematicians and computer scientists. The Research Technology team lies at the heart of the company – the CPU and GPU clusters are understandably regarded as some of the firm’s core assets, and driving their development forward is a primary focus of XTX. The research performed on the cluster is fundamental to the firm’s success.

What we are doing:

• The cluster spans multiple data-centres and accommodates multiple tenants, providing CPU and GPU for executing tasks, running services, housing LLMs etc. We are actively expanding the features and UX that we provide to quants and other teams within XTX.
• We have built and open-sourced our own exa-scale filesystem, designed to handle billions of directories, a trillion files and a million clients spanning multiple datacentres, whilst offering complete resiliency. You can read more about it here. Current projects include proving full NFS access, optimising storage services, io feature expansion (e.g. greater POSIX compatibility, creating an iSCSI target), bandwidth optimisation etc.
• We have several low-level technical projects including file system optimisation, storage performance, file compression, network segregation, as well as network, GPU and system performance management.
• Higher level projects include service failover, system and configuration deployment, hardware failure management.

Responsibilities

The Research Technology team at XTX Markets is responsible for all aspects of the firm’s HPC cluster as well as supporting the work of the quantitative researchers that use it. Although the team’s scope encompasses all aspects of infrastructure and software design, implementation and maintenance, this role is primarily focused on software development.

• Successful candidates will be self-motivated and self-starters. They will constructively engage with the team of researchers and look for novel and scalable ways of solving problems, improving resiliency and enhancing the scalability of the system.
• They will have a strong awareness of risk - not afraid to promote radical change and alternative ways of thinking, but also able to deliver solutions in a pragmatic and secure manner reducing the potential for operational failure.
• They must be prepared to work in a fast-moving environment and manage the challenges of maintaining a complex live system 24/7 whilst delivering change at short notice or to tight deadlines. Time-to-market is key.

Essential Attributes

• A solid grounding in academic CS fundamentals (algorithms and data structures).
• Proficient in at least one statically typed language; development with be using Golang and Rust though experience in these is not a pre-requisite. Scripting is mainly in Python.
• Approximately 5-10 years’ experience designing and building large-scale distributed systems; with the ability to develop highly scalable solutions to problems.
• Strong problem solving and analytical skills.
• Familiarity with the Linux operating system; able to engage in diagnosing issues, specifically those associated with performance and scalability.
• Ability to multi-task, working on multiple projects at once and prioritise appropriately across them.
• Be highly self-motivated and able to work independently without supervision.
• Understanding of one or more machine learning frameworks and compute offload devices, like GPUs, is an advantage.
  
  
  

Benefits

• Onsite gym, sauna, and fitness classes at no charge.
• Extensive medical benefits including an on-site doctor and therapist at no charge. 
• Breakfast and lunch provided daily.
• Various supports for caregivers, including emergency dependent care
• Beautiful Kings Cross office: https://vimeo.com/257888726
• 25 days paid holiday per year + statutory holiday and paid sick days. We currently operate 4 days a week in-office, 1 from home.