The death of the mainframe has often been proclaimed. But these are dinosaurs that simply refuse to die out. Nor is that particularly surprising because the mainframe offers an unbeatable combination of high availability, performance, scalability, security and large transaction volumes in the modern age of cloud computing and big data. Banks and insurance companies, in particular, still rely on this unique package. The software installed on the mainframe represents the biggest block of costs here. As the only large provider of the hardware and much of the relevant software, IBM knows how to exploit its monopoly skillfully, which leads to lock-in effects and a multitude of other difficulties.