Low-Latency Trading Infrastructure Engineer

Location: UK (Hybrid)

Type: Permanent or Contract

A1X Trading is a principal trading firm focused on the digital asset derivatives markets, using advanced technology and quantitative strategies to provide liquidity and express informed views. The firm combines systematic trading approaches with robust infrastructure to operate efficiently in fast-moving, global markets. As a boutique organization, A1X Trading offers a high-impact environment where team members can shape systems and processes directly.

The company is expanding internationally, driven by a commitment to innovation, performance, and excellence in the evolving digital asset landscape.

We are looking for a senior Linux Infrastructure Engineer to build and optimise latency-sensitive trading infrastructure, with a strong focus on bare-metal Linux, low-latency networking and exchange connectivity. The role also includes supporting AWS infrastructure, automation and connectivity across colocated and cloud environments.

• Design, deploy, optimise and maintain bare-metal Linux infrastructure for latency-sensitive trading systems that handle market data, strategy, alpha, order management and execution.
• Specify and validate hardware choices: processors, memory, storage, and network interfaces.
• Profile and tune OS components such as BIOS, CPU & IRQ affinity, NUMA node selection, huge pages, power management, NIC configuration and relevant kernel parameters for predictable performance.
• Establish secure configuration and appropriate patch-management processes.

• Own deployments in exchange colocation environments such as Equinix LD4.
• Coordinate with providers, exchanges and remote-hands teams to provision rack space, power, server and network hardware, cross-connects, and global private transport.
• Configure internal segmentation and management networks, and coordinate provider handoff requirements such as VLAN tags, port settings, and routing.
• Troubleshoot TCP/IP and UDP connectivity and investigate latency, jitter, packet loss and other performance issues.
• Ensure accurate time synchronization and packet time stamping with PTP and NIC hardware clocks.
• Design and maintain exchange-facing, latency-sensitive AWS infrastructure including instance selection and placement, enhanced networking, VPC design, packet-level monitoring, and latency diagnostics.
• Support staging, research, operations and testing workloads that rely on services such as Sage Maker, EC2, S3 and Code Artifact.
• Automate reproducible provisioning, deployment and configuration tasks with Terraform, Git Hub Actions, AWS Systems Manager, systemd, cloud-init, Python and Bash.
• Implement connectivity between cloud and colocated workloads with AWS Direct Connect or equivalent services.

• Monitor the health, performance, and availability of our infrastructure, proactively reporting and resolving incidents.
• Develop operational documentation, runbooks, monitoring, alerting, logging, backup, and disaster-recovery processes.
• Work closely with software engineers, quantitative developers, and traders to improve system performance, reliability and ergonomics.

• 5+ years of professional experience administering production Linux systems.
• Strong understanding of Linux internals and performance optimisation such as CPU pinning, IRQ tuning, NUMA placement, and kernel optimisation.
• Experience building and operating bare-metal server infrastructure.
• Strong networking knowledge, including TCP/IP, UDP, routing, VLANs, and NIC configuration.
• Experience benchmarking and troubleshooting system and network performance.
• Strong Bash, Python, troubleshooting and documentation skills.
• Experience supporting electronic trading, market-making, exchange, or market-data systems.
• Kernel bypass technologies: DPDK, Open Onload,
• Performance profiling C and C++ applications