The securities industry is characterized by complex transaction processing systems that handle multiple processes and interface with numerous upstream and downstream applications. Businesses that need to test these complex system interactions often find that their testing capabilities are not as robust as they would want them to be. Using a rigorous approach to clearly define the boundaries of systems that need to be tested, optimizing the test cases to a manageable number, and executing them effectively would provide significant benefits in the short and long term- both in terms of managing costs and also assuring the quality of software delivered, thereby reducing operational risk and risk to reputation.