Source: Lucian A. Bebchuk, Alon Brav, Wei Jiang, National Bureau of Economic Research (NBER), NBER Working Paper No. w21227, June 2015
From the abstract:
We test the empirical validity of a claim that has been playing a central role in debates on corporate governance — the claim that interventions by activist hedge funds have a negative effect on the long-term shareholder value and corporate performance. We subject this claim to a comprehensive empirical investigation, examining a long five-year window following activist interventions, and we find that the claim is not supported by the data. We find no evidence that activist interventions, including the investment-limiting and adversarial interventions that are most resisted and criticized, are followed by short-term gains in performance that come at the expense of long-term performance. We also find no evidence that the initial positive stock-price spike accompanying activist interventions tends to be followed by negative abnormal returns in the long term; to the contrary, the evidence is consistent with the initial spike reflecting correctly the intervention’s long-term consequences. Similarly, we find no evidence for pump-and-dump patterns in which the exit of an activist is followed by abnormal long-term negative returns. Our findings have significant implications for ongoing policy debates.