Mergers are back, but Wall Street's not buying the hype.

Mergers are back, but their benefits are disputed. A significant percentage of mergers destroy value for shareholders, and some have produced spectacular losses. Recent examples include Bayer's purchase of Monsanto and Chart Industries' acquisition of an air moving equipment manufacturer. In contrast, SABESP's acquisition of EMAE in Brazil is seen as a profitable investment that adds less than 2% to assets and improves the reliability of the water distribution system. Another merger, American Water Works' acquisition of Essential Utilities, may result in the gas company being sold off, raising questions about the merger's value for shareholders.