The Power of Social Media – Shareholder Activism via Twitter and a Firm’s Market Value

This paper analyzes the association of hedge fund activism via social media and a firm’s market value using Carl Icahn and Apple as an exemplary case. We apply an event study methodology for the period spanning from August 2013 to March 2015 with Apple share prices and the Dow Jones as the benchmark. An event is defined as the date whenever Carl Icahn issues a post (tweet) on his Twitter profile related to Apple. We find that some tweets lead to significant positive cumulative abnormal returns, which are robust in a number of tests. This new form of event definition contributes to prior literature that solely uses regulatory filings to define events and points towards the influence that social media may have on companies nowadays.