Before revision: Recent studies combining social media data with data from capital markets have mainly focused on the relationship between returnsand activity on social media. In contrast, we study how behavior of different investor categories are associated to Facebook posts and other activity on a company' s Facebook wall. We provide evidence that the decisions of less sophisticated investors---namely, households and URLanizations---to increase or decrease their shareholdings are associated with Facebook data , while the decisions of more sophisticated investors---financial and insurance institutions---are not associated with Facebook data .
After revision: Recent studies combining social media data with data from capital markets have mainly focused on predicting stock returns. Instead of predicting stock price movements, we examine the relation between Facebook data and investors' decision making in stock markets with a unique data on investors' transactions on Nokia. We find that the decisions of less sophisticated investors---namely, households and URLanizations---to increase or decrease their shareholdings are associated with Facebook data , while the decisions of more sophisticated investors---financial and insurance institutions---are not associated with Facebook data .