Transforming core financial processes: Billing modernization at a large investment bank

For large investment banks, core financial processes and platforms are not simply about sending invoices; they are critical engines of operational efficiency and client trust. Yet, many global investment banks grapple with outdated platforms that slow operations, miscalculate charges or lead to revenue leakage. 

This inefficiency is not just a nuisance; it’s a competitive disadvantage. And no one in financial services can afford to fall behind. 

True transformation starts with seeing beyond the immediate symptoms. Beneath outdated systems lie deep-rooted barriers that must be carefully untangled to achieve lasting change.

The legacy crisis in investment banking 

Outdated systems have more ripple effects than you might think. They delay invoicing cycles, increase operational risks and erode client trust. Small inaccuracies quickly compound into big issues for large banks handling millions of transactions and thousands of accounts. One of the most common challenges? Migrating away from these aging systems to modern platforms without disruptions.

For example, one investment bank we worked with faced multiple issues: 

• High data volume: Manually transferring data across systems created serious logistical challenges. 

• Data accuracy risks: Maintaining absolute data integrity throughout migration was critical.

• Structural data differences: Mapping inconsistent data structures from legacy systems into the new system was painstaking. 

• Limited error detection: Without efficient mechanisms to flag configuration errors early, the integrity of the entire migration was at risk.

• Business context gaps: Operations data was often structured without reflecting broader business objectives, requiring time-intensive workarounds. 

   

These hurdles are common for banks in North America, Europe and beyond. But is there a smarter way forward? 

The solution is in the details 

Success in executing a seamless systems migration, especially for large enterprises, depends on these five principles. Here’s how we approached it for our client’s billion-dollar operation. 

1. Understand the past to build the future 

Migration starts with discovery. The legacy system held extensive data structures encompassing client accounts, pricing schemes and transaction rules. A direct, one-to-one migration wasn’t feasible due to differences in data structures and formats between the systems. We mapped 80% of the data directly while actively identifying inconsistencies in the remaining 20%. 

By taking the time to truly understand how the data intertwined with the bank’s business practices, we aligned operations and created a clear path forward. 

Takeaway: Invest time upfront to fully audit, document and map old to new data structures. It’s not glamorous, but it’s essential. 

2. Leverage smart automation 

Big challenges demand smart solutions. For our client, more than a million data points needed to flow seamlessly into a new billing system. We used advanced AI technology for mapping, migration and validation, dramatically reducing manual effort while proactively flagging errors before they became systemic issues. 

Downtime was practically eliminated by using parallel billing runs. This approach involved generating test bills from both old and new systems, running error checks automatically, and improving accuracy through continuous validation cycles. 

Takeaway: AI technology can shrink timelines and costs. Use scripts and AI-powered tools for error detection and validation wherever possible. 

3. Validate, validate, validate 

Validation is a continuous, cyclical process, not a singular event. At critical migration points, each record was verified against a collaboratively defined 'source of truth'. Discrepancies were immediately resolved which minimized downstream risks.

By the time the system went live, the bank’s diverse client base - 4,000 accounts across 30,000 individual lines was fully mapped. 

Takeaway: Adopt a rigorous, ongoing validation process. Never assume source system data can be trusted without deep, granular review. 

4. Overcome structural complexity 

Investment banking rarely offers simplicity. The sheer volume of transaction rules, unique product types and nested pricing arrangements demanded extensive customization. During migration, legacy patterns that didn’t align cleanly with the new system created billing complexities. Through simulation exercises and mock trials, we refined the onboarding process and created downstream reporting to cross-check migrated data. This iterative refinement was key to uncovering and resolving deeply embedded inefficiencies. 

Takeaway: Be adaptable. Structure discrepancies will arise. Rely on mock trials and iterative performance checks to overcome hidden complexities. 

5. Keep the bigger picture in view 

Billing isn’t just operational; it’s strategic. Migration presented opportunities to transition the bank toward flexible pricing, bundled product offerings, and even multi-currency settlement. Initiatives once considered impossible are now on the table, transforming billing from a backend function into a competitive differentiator. 

Takeaway: Use migration projects as a launchpad for innovation - and a chance to unlock future revenue potential.

Results that speak for themselves 

By upgrading to a modern billing platform, our client saw instant improvements, including: 

• 50% faster billing cycle times. 

• Automated billing setup for reduced operational overhead. 

• Significant reduction in risks and vulnerabilities.

• Customizable billing features enabling flexible pricing to suit multi-product enterprises. 

• Revenue recovery from previously overlooked transactions.

Solve big problems, make bold moves 

At Thoughtworks, we understand that billing migration demands innovation, precision, and bold thinking. We’ve proven our ability to transform complex systems into future-ready solutions for our clients. 

Is outdated legacy tech holding your business back? It’s time for a change. Partner with us to take the first step toward operational excellence and long-term growth. 

Contact us today and modernize your systems for tomorrow.