Banking platforms are critical business infrastructure, and many banks today need to transform their banking landscape to remain fully competitive. But quantitative benefits late in a transformation often do not fully compensate for huge early investments. Banks must also consider risk: Banking platform transformation is similar to brain surgery — although the operation typically takes a couple of years and the patient needs to remain fully conscious throughout. This case study describes how a major bank in Europe planned its transformation approach and designed a transformation architecture to gradually transform its banking platform while optimizing the balance of investments and transformation benefits.