Citadel Securities is seeking a Senior Platform Infrastructure Engineer to design, build, and maintain scalable infrastructure supporting critical trading systems. The role involves collaborating with cross-functional teams to optimize performance, reliability, and security of platform services. Candidates should possess strong expertise in distributed systems, Linux, networking, and automation tools, along with experience in high-frequency trading environments. This position is based in New York and offers an opportunity to work in a fast-paced, innovative financial technology firm.