Ecosystems are one of the major trends today. They are based on complementarities, which can take the form of supermodularity or uniqueness and appear on both production and consumption side. Different configurations of complementarity lead to different characteristics of ecosystems with different implications. But which configuration of complementarities is beneficial in a given setting and what are the resulting consequences? We study emerging ecosystems driven by the respective orchestrator. Based on a multiple-case study, we show how and why orchestrators are leveraging different configurations of complementarities depending on, amongst others, competition on ecosystem or value proposition level and uncertainty and the resulting challenges for the orchestrator. These insights provide researchers with a better understanding of the basic mechanics of ecosystems and explain why certain types and structures of ecosystems are more likely to be seen in specific environments. For managers, it helps to sketch the development paths for own ecosystems.