Blue Walker Capital is a proprietary trading firm developing systematic and quantitative trading strategies native to prediction markets.We log billions of trades and order book ticks per day, isolate market pairs from hundreds of millions of combinations, and continuously monitor for a range of market inefficiencies we execute on. It's still early days for us—we are deepening a moat across trading infrastructure, datasets, and modeling.We trade algorithmically using our own balance sheet, generating daily returns exceeding 1% with the capacity to rotate hundreds of thousands of euros in daily volume.Our mission is to become the leading hedge fund in this emerging asset class, delivering investment returns while making prediction markets efficient as the world's most accurate source of truth.Backed by world-class investorsDaniel Howard is the Founder and Managing Partner of Halo Capital, a digital assets venture fund associated with Brevan Howard. Previously, he was a Principal at 10 T Holdings, a Machine Learning Engineer at Spark Cognition, and a Data Scientist at Verisk. Daniel also spent over seven years in academia across Columbia University’s Engineering and Business schools.Wouter Gort - Hummingbird VenturesWouter Gort is a Partner at Hummingbird Ventures, where he leads Nomads, the firm's fund-of-funds. Previously, he co-founded Greyhound Capital and led investments in companies such as Revolut, Toss, Brex, N26, and Marqeta. Wouter also seeded a startup hedge fund that was acquired by global market maker IMC Trading in 2023.About the RoleWe are a small engineering team, which means your responsibilities scale rapidly and your impact is clear and foundational. You would own the execution path end to end: order submission, fill handling, position tracking, reconciliation, and the risk controls around them.The stack spans two languages. Python covers services where iteration speed matters most;
Rust covers latency-critical and concurrency-heavy components.ResponsibilitiesOwn the order execution path: submission, fills, cancellations, retries,



and the state machine tracking order lifecycle.Build and maintain risk controls: exposure limits, drawdown monitoring, kill switches, and their alerting.Profile and optimise latency-sensitive paths, with measurements before and after.Make forward-looking architectural decisions, balancing risk, performance, cost, and maintainability. We offer flexibility, not hand-holding.Stress-test and strengthen critical systems for robustness and clarity. A dependable existing feature set matters more to us than new features.Extend the platform to new venues and instruments as our research grows.Who we are looking forHard Skills2+ years of hands-on production experience in Python, including asyncio, Web Socket clients, and event-loop behaviour under sustained load.Production experience in Rust, with demonstrated work. Ownership, borrowing, lifetimes, traits, and generics.Async Rust: Tokio, Send/Sync bounds, cancellation safety, and the effect of blocking work on an async runtime.Concurrency: message passing versus shared state, channel and lock selection, atomics and memory ordering.Experience with systems where state correctness is a primary requirement: idempotency, retry semantics, and reconciliation against an external source of truth.Relational databases and in-memory stores (Postgres, Redis, or equivalent): schema design, indexing, and transactional boundaries.Working knowledge of Op Sec practices, secrets management, in both personal workstation and production environments.Docker and Docker Compose, and the Dev Ops needed to provision servers, run and supervise long-lived services, configure networking, and work in Linux.Ability to design and write production-grade systems without LLMs,



while being proficient and deeply integrated with AI tools to maximize development velocity.A background in statistics, computer science, mathematics, physics, or other quantitative fields.Soft SkillsSelf-starter with intense intellectual curiosity.Preference for diagnosing a live system over deploying a speculative fix.Comfort working on code you did not write and cannot fully rewrite.Preferred SkillsPrior integration with exchange or broker APIs, and experience with order management or execution systems.Market microstructure: order books, fee structures, slippage, and execution quality measurement.Performance measurement with flamegraphs, perf, criterion, and latency histograms, reported at p99 and p99.9.Lock-free structures: SPSC/MPSC ring buffers, bounded queues, and cache-line and false-sharing effects.Thread-per-core or shared-nothing designs, and core pinning.Property-based and deterministic testing of concurrent code: proptest, loom, fuzzing, or replay against recorded feeds.Rust–Python interop via Py O3 or FFI.Observability: metrics, structured logging, and tracing.Experience inheriting and hardening systems you did not write.What it’s like hereFast paced environment.We’re direct and honest with each other.5 days a week, in person. Full immersion.Project ownership and autonomy, flat company structure.We value people who take initiative and are able to figure things out.Company culture is informal, non-hierarchical, ambitious, collaborative and entrepreneurial.CompensationCompetitive compensation, tailored to ability and experience.5' to Transport & GymCutting-edge InfraTeam OffsiteFlexible HolidaysSpecial EventsPressFrom Spain to the WorldTalent is evenly distributed. Opportunity is not. Spain produces world-class technical talent, but the local market rarely provides the opportunities to unlock exponential careers. At Blue Walker Capital, we build for exponential outcomes. Join us as we expand our footprint across general capital markets and put Spain on the map of excellence.

📌 Trading Systems Engineer (Barcelona)
🏢 BlueWalker Capital
📍 Barcelona