This study addresses the question of the constitution of markets in advanced societies. Specifically, the article studies the role of the traveling trade show in creating the real time computing market, which is part of the US electronics sector, during the mid-1990's. Real time computing products assist the transfer, storage and processing of digital signals in real time and support many of the internet applications we use today. By applying ethnographic methods, we explore the general question of how economic actors cope with uncertainty in the phase of market-making and at the cutting edge of technology. The paper makes two contributions to the existing literature. First, it shows that the attempt to organize a trade show in real time computing was triggered by the uncertainty experienced by sellers regarding the identity of prospective buyers and about the exact use to which they would put the emergent technology which is offered for sale. Secondly, we trace the history of an emergent market. We claim that trade shows for innovative products are important venues at which markets coalesce. The identification and ordering of market actors, the institutionalization of a distinct business culture and the social networks developed among market actors and across the subsidiary markets provided the basic social infrastructure for what later became known as the real time computing industry.