Purpose The present study aims to contribute to the growing stream of literature about the network perspective of value co-creation via key account management (KAM) by exploring how firms, in complex industrial markets, use key account strategies to create value, not only for buyers and sellers of industrial products/services but also, more widely, for larger ecosystems of stakeholders. The research question this paper seeks to address is how the KAM approach promotes value co-creation in multi-stakeholder ecosystem. Design/methodology/approach To answer this research question, this study uses a qualitative research approach based on data triangulation. This study focuses on the market access (MA) strategies implemented by a multinational UK-based pharmaceutical company within the Italian multi-stakeholder health-care ecosystem over several years. Findings The results show that KAM in complex networks acts as a catalyst for value creation, through multiple interactions with different actors and an ad hoc configuration of five strategic levers: product performance, economic impact, institutional relationships, commercial organization and communication. These levers are able to unlock the appropriate value drivers and form a specific "market access mix" implemented by the firm to both promote the adoption of the firm's products and generate value for all market stakeholders. Originality/value The study offers an innovative and comprehensive evidence-based model for designing specific MA strategies aimed at co-creating value within multi-stakeholder ecosystems. The proposed MA mix outlines the fact that knowledge, relationships and innovation are not unique factors that can be leveraged by stakeholders to co-create value.