Merger and Acquisition Performance Event Study

A merger and acquisition event study measures the stock-market reaction to a deal announcement to infer how much value the deal is expected to create or destroy for acquirers and targets. The logic is that in an efficient market the share-price jump around the announcement capitalizes investors' revised expectations of future cash flows attributable to the deal. Andrade, Mitchell and Stafford's 2001 survey distilled the empirical regularities: targets earn large positive abnormal returns, combined acquirer-plus-target returns are modestly positive, while acquirers themselves often earn around zero or slightly negative returns. King, Dalton, Daily and Covin's 2004 meta-analysis confirmed that acquirers, on average, do not gain and pointed to unidentified moderators, motivating cross-sectional models that link abnormal returns to deal and firm characteristics.