For decades, trading technology has been haunted by large, intricate, all-in-one applications that power core business functions, aka the monolith. While once a necessity, these systems have become a source of immense friction. They are brittle, expensive to maintain, and notoriously slow to change, creating a chasm between business demands for agility and IT’s capacity to deliver.
But a new, more pragmatic path to modernization is emerging. At A-Team Group’s recent TradingTech Briefing New York, a series of discussions with architects and technology leaders from across the industry laid out a clear, experience-tested guide for slaying the monolith without embarking on a high-risk, ‘big bang’ rewrite. The consensus is clear: the future is modular, but the path to get there must be incremental, value-driven, and intensely practical.Step 1: Decompose the Workflow, Not Just the Application
The first step away from the monolith isn’t to tear the entire system down, but to strategically break it apart. A compelling case study shared by a major Canadian bank detailed their journey of modernising a legacy precious metals trading platform. Instead of attempting a full rebuild, their team focused on the user’s actual workflow. They observed the manual, error-prone process of copying orders from emails into spreadsheets and targeted that specific pain point.
By decomposing the monolith into a series of small, interconnected ‘micro-UIs,’ they created a hyper-optimised workflow. A new order entry widget reduced a 30-second task to seven. A copy-and-paste feature for sales teams turned minutes of rekeying into a five-second action. This approach delivered immediate, measurable value and, crucially, rebuilt trust with the business, proving that modern architecture is less about the application itself and more about the efficiency of the human using it.
Step 2: Embrace the Middle Ground with ‘Macroservices’
While the industry buzzes with talk of microservices, a frank discussion among senior technologists offered a critical dose of realism. For many firms, a full decomposition into hundreds of tiny, independent services is a leap too far, too soon. It introduces immense complexity and requires a specialized skill set that teams accustomed to maintaining monoliths often don’t possess.
“If you try to take some big problem and boil the ocean and create a thousand microservices, you’re going to fail,” warned a technology leader at a global bank. He instead championed the concept of macroservices. This pragmatic middle ground involves breaking a monolith into larger, more manageable components. It delivers, in his estimation, “70 or 80% of the value” of a full microservices architecture with a fraction of the risk. This approach allows development teams to learn the principles of modular design on a more forgiving scale before diving into the deep end of distributed systems complexity.
Step 3: Adopt a “Buy and Build” Philosophy
Underpinning this new architectural approach is a fundamental shift in procurement and development philosophy from a binary ‘buy versus build’ choice to a hybrid ‘buy and build’ strategy. The mantra, as one vendor CEO put it, should be: “You only write code because you have to.”
The idea is to buy a foundational development platform that handles the commoditised, non-functional heavy lifting, such as data stream handling, entitlements, session management, and UI rendering. This is the complex, undifferentiated plumbing that every trading system needs but which provides no competitive advantage. By buying this layer, firms free up a valuable resource – their in-house developers – to focus exclusively on building the bespoke business logic and unique features that actually drive revenue and differentiate them from the competition.
The Result: A Flywheel of Success
This three-step approach – decomposing workflows, starting with macroservices, and leveraging a buy-and-build platform – does more than just modernise technology. It transforms the relationship between IT and the business. When technology teams can deliver tangible value in 30-day sprints instead of 18-month project cycles, they shift from being a slow-moving cost centre to an agile, responsive partner.
This creates a ‘flywheel effect.’ Each small, successful delivery builds credibility and excitement, which in turn generates demand for more innovation. This virtuous cycle, grounded in pragmatic architectural choices, is how Wall Street is finally beginning to slay the monolith and build a more agile and resilient future.
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