The existing literature on the post-merger performance of acquiring firms is divided. The authors reexamine this issue, using a nearly exhaustive sample of mergers between NYSE acquirers and NYSE/AMEX targets. The authors find that stockholders of acquiring firms suffer a statistically significant loss of about 10 percent over the five-year post- merger period, a result robust to various specifications. Their evidence suggests that neither the firm size effect nor beta estimation problems are the cause of the negative post-merger returns. They examine whether this result is caused by a slow adjustment of the market to the merger event. Their results do not seem consistent with this hypothesis.

The existing literature on the post‐merger performance of acquiring firms is divided. We re‐examine this issue, using a nearly exhaustive sample of mergers between NYSE acquirers and NYSE/AMEX targets. We find that stockholders of acquiring firms suffer a statistically significant loss of about 10% over the five‐year post‐merger period, a result robust to various specifications. Our evidence suggests that neither the firm size effect nor beta estimation problems are the cause of the negative post‐merger returns. We examine whether this result is caused by a slow adjustment of the market to the merger event. Our results do not seem consistent with this hypothesis.