Is it true that most of them turn out to be failures?

The answer to this question depends on how you define failure. Scholars have published hundreds of studies of postmerger financial performance, and few have defined failure—or, conversely, success—in exactly the same way.

On average, M&A has a neutral effect on share prices, with some companies losing value and others gaining it—especially serial acquirers. A classic study in this regard is one by Darden Business School dean Robert Bruner, whose comprehensive review of M&A research—covering more than 100 studies—found that in general:

• Shareholders of selling firms earn large returns.
• Shareholders from buyers and sellers combined earn significant returns.
• Shareholders of buyers usually earn the required rate of return.

Some studies ask the acquirers themselves to judge their postmerger success. A 2023 study from PWC found that most acquirers believed that their recent deals had been successful or moderately successful, although they gave higher ratings for their strategic and operational success than for their financial success.