Business and research likewise acknowledge the potential and economic value of information exchange in social media (i.e. the quality and the quantity of user-generated content). While existing research has mainly focused on the analysis of the impact of online information exchange, little attention has been devoted to the drivers of information exchange in social media related to major business events. In this study we explore drivers of information exchange relating to such events. In the context of merger-acquisition events, we posit that firm visibility based on firm characteristics and information needs triggered by the event itself influence the information quantity generated in social media. We test these hypotheses using a rich data set that includes a wide range of social media types and platforms. Our results show that both firm visibility and information needs are driving information quantity in social media in the context of corporate actions. Both of these driving factors are highly significant in explaining the information quantity in social media.