London | Hybrid | Tier 1 Investment Bank The Opportunity We are partnering with a Tier 1 investment bank on a major, multi-year Equity Accelerator programme focused on modernising its Prime Finance Equities platform. The programme is re-engineering core trading and post-trade systems, introducing new data and market-expansion platforms, and enabling advanced client capabilities including cross-margining and credit financing . You'll be working within a live, financially significant production environment , replacing legacy architecture with modern event-driven, cloud-native systems designed for institutional-grade stability, throughput and extensibility. This is not a general-purpose Java development role. The team requires engineers with strong technical depth, genuine capital-markets experience and the ability to operate autonomously within a complex production environment. Essential functions The Role As a Senior Java/Kotlin Engineer , you'll contribute to the re-engineering of core Prime Finance trading and post-trade systems across the JVM ecosystem. You'll work closely with experienced engineers and business stakeholders, contributing to architectural decisions, modernising legacy components and building highly resilient services capable of handling complex financial workflows and market-driven events. Key Responsibilities Re-engineer core trading and post-trade systems using Java and Kotlin Design and develop event-driven, message-based and event-sourced systems Design for failure handling, ordering guarantees, replay semantics and data integrity Modernise and refactor large-scale legacy systems while maintaining production stability Build data and market-expansion platforms supporting the wider Equity Accelerator programme Develop technology supporting advanced capabilities such as cross-margining and credit financing Apply TDD and shift-left testing throughout the development lifecycle Build local-first automated tests using containerised dependencies Deliver through trunk-based development and CI/CD Support frequent, zero-downtime production releases Work directly with business stakeholders and upstream/downstream teams to develop strong domain knowledge Analyse complex production behaviour and resolve technically challenging issues Use AI-assisted and agentic development tools to accelerate legacy analysis, refactoring, testing and prototyping Contribute to technical design discussions and challenge decisions constructively where appropriate Qualifications Essential Experience Expert-level Java development experience Strong experience with Kotlin , or a clear appetite to develop in Kotlin Strong understanding of multi-threading, concurrency and performance Hands-on experience designing and developing event-driven systems Practical understanding of message passing, event sourcing, failure handling, ordering and replay Proven Test-Driven Development (TDD) experience Strong automated testing and design-for-testability practices Experience within capital markets, trading or post-trade environments Strong understanding of areas such as: Trade lifecycle Trade booking Position management Cashflow calculation Settlement and wires Client reporting Financial accounting principles Experience modernising and refactoring large-scale legacy systems Genuine experience working with iterative delivery, trunk-based development and CI/CD Experience delivering frequent, reliable zero-downtime production releases Ability to work autonomously within complex production environments Strong communication skills and the confidence to contribute to architectural and technical decisions Technology Environment Java | Kotlin | JVM | Event-Driven Architecture | Event Sourcing | Kafka | SQL Server | T-SQL | MongoDB | Kubernetes | OpenShift | Cloud | OpenTelemetry | ELK | Grafana | CI/CD | TDD | Git | Trunk-Based Development | Docker | AI-Assisted Development The Opportunity This is an opportunity to work on a strategic, multi-year transformation at the heart of a global Prime Finance business , rather than simply maintaining an existing application. You'll gain deep exposure to Equity Prime Finance, trading and post-trade technology , work alongside highly experienced engineers and play a meaningful role in replacing legacy systems with modern, resilient and scalable architecture. If you're a senior Java engineer who combines deep engineering ability with genuine capital-markets domain knowledge , this is an opportunity to work on technically challenging systems with significant business impact. Would be a plus Highly Desirable Prime Brokerage experience Synthetic / Swap or Cash Equity operational flows Corporate Actions Regulatory reporting, including 871(m), EMIR or MiFID Integration with risk and valuation systems Strong SQL Server / T-SQL experience Database schema design and performance tuning Kafka or equivalent event-streaming platforms at scale MongoDB Kubernetes / OpenShift Cloud-native operational practices OpenTelemetry, ELK and Grafana AI-first development using agentic coding tools for legacy analysis, refactoring and test generation We offer Opportunity to work on bleeding-edge projects Work with a highly motivated and dedicated team Competitive salary Flexible schedule Benefits package - medical insurance, sports Corporate social events Professional development opportunities Well-equipped office About us Grid Dynamics (

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GDYN) is a leading provider of technology consulting, platform and product engineering, AI, and advanced analytics services. Fusing technical vision with business acumen, we solve the most pressing technical challenges and enable positive business outcomes for enterprise companies undergoing business transformation. A key differentiator for Grid Dynamics is our 8 years of experience and leadership in , supported by profound expertise and ongoing investment in , , , and . Founded in 2006, Grid Dynamics is headquartered in Silicon Valley with offices across the Americas, Europe, and India.