Low Latency Trading Infrastructure Engineer

About Citi:

Citi, the leading global bank, has approximately 200 million customer accounts and does business in more than 160 countries and jurisdictions. Citi provides consumers, corporations, governments, and institutions with a broad range of financial products and services, including consumer banking and credit, corporate and investment banking, securities brokerage, transaction services, and wealth management.

As a bank with a brain and a soul, Citi creates economic value that is systemically responsible and in our clients' best interests. As a financial institution that touches every region of the world and every sector that shapes your daily life, our Enterprise Operations & Technology teams are charged with a mission that rivals any large tech company. Our technology solutions are the foundations of everything we do from keeping the bank safe, managing global resources, and providing the technical tools our workers need to be successful to designing our digital architecture and ensuring our platforms provide a first-class customer experience. We reimagine client and partner experiences to deliver excellence through secure, reliable, and efficient services.

Our commitment to diversity includes a workforce that represents the clients we serve from all walks of life, backgrounds, and origins. We foster an environment where the best people want to work. We value and demand respect for others, promote individuals based on merit, and ensure opportunities for personal development are widely available to all. Ideal candidates are innovators with well-rounded backgrounds who bring their authentic selves to work and complement our culture of delivering results with pride. If you are a problem solver who seeks passion in your work, come join us. We'll enable growth and progress together.

About the Team:

The Low Latency Trading Infrastructure Engineer is a rare combination of deep technical specialist and mission-critical operator — a professional whose expertise sits at the intersection of hardware engineering, financial markets technology, and performance science. This role sits at the heart of Citi's Global Equity Markets technology organization, responsible for designing, delivering, and sustaining the ultra-low latency infrastructure that powers one of the world's most demanding electronic trading environments. The candidate we seek does not merely maintain infrastructure — they engineer deterministic performance at nanosecond precision, shaping the technical foundation upon which Citi competes in global markets. This is a position for seasoned practitioners who have thrived in high-frequency trading firms, exchange technology groups, or HPC environments, and who bring a rare depth of knowledge spanning bare-metal compute, kernel-bypass networking, FPGA-enabled hardware, and exchange colocation operations.

The successful candidate will operate at the nexus of infrastructure engineering and trading performance, collaborating closely with application development teams, trading desks, risk and compliance stakeholders, and exchange and colocation facility partners. They will drive end-to-end latency optimization across the full trading stack — from BIOS tuning and NIC configuration through to circuit provisioning and market data distribution — while ensuring that every environment meets Citi's stringent standards for security, resiliency, and regulatory compliance. Their impact will be felt in every microsecond saved and every market opportunity captured, contributing directly to Citi's standing as a premier global equities trading institution.

Technical Responsibilities:

• •Design low-latency compute topologies including bare-metal servers, NICs, kernel bypass technologies such as DPDK and Solarflare, and FPGA/co-location hardware
• •Evaluate CPU microarchitecture, NUMA topology, cache behavior, and memory bandwidth characteristics for trading workloads
• •Define hardware and firmware standards in partnership with vendors including Dell, HPE, Mellanox/NVIDIA Networking, Arista, Cisco, and Juniper
• •Design and maintain custom server build patterns tailored to the low-latency trading platform, distinct from Citi's standard enterprise server catalog
• •Establish and enforce standards for low latency Linux, Windows, and Microservice infrastructure, including OS optimization, kernel bypass technologies, CPU isolation, NUMA optimization, interrupt tuning, and deterministic performance engineering
• •Build repeatable benchmarking harnesses to measure tick-to-trade latency, jitter, and throughput
• •Conduct comparative hardware, firmware, and BIOS tuning analysis including CPU pinning, IRQ affinity, C-state/P-state tuning, and huge pages configuration
• •Correlate benchmark results with real trading telemetry to validate production readiness
• •Drive packet capture analysis and latency telemetry across the full trading stack
• •Architect and deliver high-performance colocation environments connecting exchange venues, market data providers, and internal trading systems
• •Implement ultra-low latency Layer 1/Layer 2 network configurations across trading infrastructure
• •Execute formal certification test plans for new hardware, firmware, and OS/kernel builds before production introduction
• •Maintain audit-ready certification documentation aligned to internal risk and compliance standards
• •Coordinate with Risk, InfoSec, and Exchange/Venue technical teams where co-location or vendor certification is required, including adherence to CAT and MiFID II requirements for time synchronization, monitoring, and reporting
• •Execute infrastructure provisioning and deployments within air-gapped or network-segmented environments with no direct internet access
• •Manage image and firmware distribution via approved offline or tightly controlled transfer mechanisms
• •Apply strict change management and rollback procedures given the production sensitivity of the environment
• •Deploy and support connectivity circuits to external clients and exchanges, including cross-connect provisioning and handoff validation at specialized and co-located data centers
• •Lead bare-metal automation, deployment pipelines, and infrastructure-as-code practices using tools such as Ansible, Terraform, and Puppet for rapid, repeatable infrastructure delivery
• •Manage and configure Active Directory, ISA, DNS, PTP, Remote Access Solutions, and infrastructure management and monitoring technologies such as Lenovo LXCA, HPE OneView, Dell OpenManage Enterprise, and HCL BigFix
• •Monitor compute health, latency drift, and hardware degradation using specialized low-level telemetry tools
• •Manage hardware lifecycle refresh planning including hardware aging, EOL firmware tracking, and vendor support contract coordination
• •Troubleshoot at the hardware, OS, and network stack level under time-sensitive, high-impact conditions, often during live market hours
• •Manage Kubernetes cluster operations and workload orchestration for trading-adjacent microservice infrastructure
• •Implement and maintain high-speed interconnects including InfiniBand, RDMA over Converged Ethernet (RoCE), and multicast networking protocols

Non-Technical / Leadership Responsibilities:

• •Collaborate with application development and support teams to optimize end-to-end trading latency and infrastructure determinism
• •Participate in incident management and infrastructure resiliency efforts for mission-critical trading environments, including structured post-incident documentation and root cause analysis
• •Maintain close partnership with software delivery teams, Citi's enterprise technology group, and trading functions throughout the end-to-end platform delivery and deployment lifecycle
• •Produce meticulous documentation to support audit and regulatory review, including change requests, incident reports, and certification approval packages
• •Represent engineering requirements and infrastructure risk clearly in written communications to cross-functiona