With capital markets evolving towards 24/7 trading, the transition from monolithic platforms to agile architectures is becoming imperative as demands for performance, resilience, and integration increase. So how should trading firms architect their systems to support 24/7 markets? What are the most effective strategies for migrating away from legacy platforms? And how can firms modernise trading architectures without sacrificing predictability, control, or performance?
These were some of the key questions explored during a panel discussion at the A-Team Group’s recent TradingTech Summit London. The session, “Transitioning from Monolithic to Agile Architectures for High Performance Trading Systems,” was moderated by Irina Sonich-Bright, Managing Director, Head of Market Access Product, Agency Trading at UBS. Panellists included Anthony Warden, MD, Citi Tech Fellow – Global Head of High Performance Architectures at Citi; Minhaj Ahmed, Cash Equity Product Owner at HSBC; Deepak Dhayatker, Chief Technology Officer at Rapid Addition; and Jon Butler, Co-Founder & CEO of Velox.
Reframing Agility: Beyond Buzzwords
The panel opened with a necessary clarification: the term “agile” carries baggage. As one speaker noted, “I have a general problem with the word agile.” The concern is that its widespread use – often associated with development methodologies – can obscure its architectural meaning.
In the context of high-performance trading, agile architecture isn’t about iterative sprints or daily stand-ups. Instead, it refers to modular, adaptable systems that can evolve with changing requirements, integrate third-party components where appropriate, and support high performance at scale. These architectures must navigate a triangle of trade-offs: cost-efficiency, adaptability, and performance.
Trading Off Trade-Offs
Speakers emphasised that architectural decisions are inherently contextual and driven by competing priorities. For firms operating in latency-sensitive environments, performance may dominate. In contrast, firms prioritising regulatory compliance or explainability may favour architectures that emphasise predictability and testability.
One panellist articulated the need to “balance competing and conflicting design forces.” They noted that achieving low-latency execution does not preclude the need for testability and explainability, especially under increasing regulatory scrutiny. The challenge lies in engineering solutions that achieve both.
Event sourcing was cited as one design pattern that supports this dual objective. For specific latency targets (e.g. 2–200 microseconds at the 99th percentile), event sourcing enables traceable transaction processing without sacrificing performance. Where software alone can’t meet latency requirements – particularly in the sub-microsecond range – firms are turning to programmable hardware.
From Vendor Lock-In to Modular Control
A key characteristic of agile architecture is strategic independence. Organisations are increasingly wary of becoming beholden to large platform vendors. As one panellist observed, “We want to control our destiny, but also take advantage of good vendor solutions without getting locked in.”
This implies an architectural preference for decoupled components and open standards; design choices that allow firms to selectively integrate best-in-class third-party tools while preserving long-term flexibility. It also reflects a broader industry shift towards ‘platform thinking’, i.e. developing internal frameworks that can support diverse business logic across trading desks while maintaining coherence and reuse.
Designing for 24/7 Trading
The discussion framed 24/7 trading as a catalyst for architectural transformation. As extended trading hours move from fringe consideration to mainstream expectation, legacy monolithic systems are struggling to keep up.
Polls conducted during the session revealed that resilience and high availability were among the top concerns associated with this shift. Traditional systems – optimised for fixed trading windows – often lack the fault tolerance required for continuous operation. Agile architectures, by contrast, are better suited to distribute load, isolate failures, and automate recovery processes.
Speakers agreed that simply optimising existing tech stacks is not enough. The prevailing sentiment was that firms must “reassess and upgrade” their core platforms for long-term sustainability. This may involve re-platforming around event-driven or microservices-based paradigms, adopting cloud-native patterns, or investing in internal developer platforms to accelerate delivery.
The Human Dimension of Transformation
Underlying the technical discussion was a recurring theme: transformation is not purely a technology problem. Agile architectures demand new organisational behaviours, such as cross-functional collaboration, shared accountability, and a tolerance for experimentation.
However, trading firms cannot afford chaos. As one speaker succinctly put it, “We need predictability.” This duality – of needing both agility and control – remains a defining tension for capital markets technology leaders.
To navigate it successfully, firms must cultivate architectural discipline. This includes clearly articulating design goals, standardising core infrastructure components, and investing in observability and testing frameworks that ensure systems behave as expected, even under load or during failure scenarios.
Non-Linear Evolution
Transitioning from monolithic to agile architectures is not a linear upgrade. It is a strategic evolution driven by performance demands, operational complexity, and regulatory pressures. For high-performance trading firms, the architectural choices made today will shape their adaptability and competitiveness for years to come.
The message from the panel was clear: agility is not about moving fast for the sake of it. It’s about building systems that are resilient, transparent, and engineered for change.
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