Mergers and acquisitions are clearly the favorite corporate growth strategy of this generation's executive teams. But there is little evidence that such strategies have paid off for the acquiring companies' shareholders-and many transactions have proved disastrous for the careers of the...

When a major acquisition is announced, investors try to understand where the value is going to come from and whether the acquirer has a plan to achieve that value. Deals are often brought to market with one big synergy number and a statement that the deal will be "accretive" to earnings. The...