This article examines start-up entrepreneurialism and provides insights into the configurations of affective capitalism. The empirical case explored in this article is the Slush Conference, which promotes start-up entrepreneurialism. The data were gathered by ethnographic methods, including on-site observations, and complemented by diverse materials such as social media content and newspaper coverage of the event. Drawing upon our detailed analysis, we concluded that Slush comprises overlapping elements that constitute a novel kind of entrepreneurial enterprise: an emphasis on affective atmospheres, the articulation of an alleged affective morality and a view of affects as directly productive. These three aspects together further shed light on the nuanced operations of mood, which we consider an important manifestation of collective affects. In particular, mood plays a significant role in the shifting terrains of Nordic welfare states, where tensions between public expertise and private innovations can be identified. Furthermore, we argue that Slush is a field-configuring event that has a crucial impact on the evolution of start-up entrepreneurialism by constituting the Finnish landscape of affective capitalism.