The Post-Merger Performance Puzzle

While the bulk of the research on the financial performance of mergers and acquisitions has focused on stock returns around the merger announcement, a surprisingly, large set of papers has also examined long-run stock returns following acquisitions. We review this literature, concluding that long-run performance is negative following mergers, though performance is non-negative (and perhaps even positive) following tender offers. However, the effects of both methodology (see Lyon, Barber & Tsai, 1999) and chance (see Fama, 1998) may modify this conclusion. Two explanations of under performance (speed of price-adjustment and EPS myopia) are not supported by the data, while two other explanations (method of payment and performance extrapolation) receive greater support.