The business model concept has attracted considerable interest from researchers and practitioners alike. It is increasingly considered to be a major driver of innovation, inheriting the potential to create competitive advantage. More recent studies observed that a firm can operate multiple business models simultaneously, that is, business model portfolios. However, the unit of analysis when it comes to the investigation of relationships was exclusively represented by resources so far. The exclusion of further potential sources of synergies from research has led to a narrow perspective when it comes to the number and types of business model relationships identified. Considering that a business model describes the logic of a business it seems that the business model concept was overly simplified within the business model portfolio research stream. In fact, the original complexity of the business model concept becomes especially evident within the general business model literature and is particularly mirrored in the difficulty to agree on a common definition of the concept. However, by solely focusing on resource synergies in the business model portfolio literature, the scope of the concept gets dismissed and other possibly valuable synergistic factors during diversification processes are not apparent anymore. Another oversimplification observable within the business model portfolio research stream is the lack of differentiation made between complementary and similar components. Considering that these two concepts are entirely different by definition, their effect on business model performance most probably differs too.  This thesis will contribute to the newly emerging research stream by using a case-study approach to investigate the business model portfolio of a large European logistics player. It broadens the perspective on business model relatedness within business model portfolios by including potential relationships between customer value propositions and profit formulas next to resources and processes to the analysis. Eventually, the framework presented in this thesis combines existing literature on similarity, complementarity and conflicts with research on business models and business model portfolios in order to derive insights about the ideal types of business model portfolio compositions. The contribution of this thesis lies in proposing further approaches for business model diversification. It extends the current body of literature by adding more dimensions to the business model diversification discussion, arguing that the current view does not acknowledge the full scope and potential of the business model concept. Therefore, this thesis intends to contribute to the emerging research stream on business model portfolios by 1) closing a research gap regarding complementarity and similarity of business models and by 2) introducing additional components that might lie the basis for diversification decisions next to resources