Abstract
Research on market shaping has highlighted how firms actively transform their operating environments, yet most studies emphasize individual focal actors and contemporary contexts. This paper advances understanding of collaborative market shaping by theorizing the role of organizational hybridity and legitimizing boundary work as core mechanisms that enable collective strategies to emerge and diffuse across markets. We argue that organizational hybridity allows firms to balance autonomy with coordination, while legitimizing boundary work reframes collusive features as legitimate cooperation. Empirically, we analyze voluntary retail chains (VRCs) in Sweden between 1945 and 1975, drawing on nearly 2,700 archival documents and 38,000 pages of trade journals. We show how VRCs coordinated procurement, branding, and access to retail space, thereby reshaping the regulatory and competitive contours of multiple markets. Our findings expand the empirical and methodological base of market shaping research and highlight the value of historical analysis for understanding how firms navigate Knightian uncertainty.