A wave of corporate breakups has rippled through industry after industry over the past several years. This has happened in consumer goods, for instance, with Kraft Foods’ spin-off of its North American grocery business; in materials, with Alcoa’s split into separate aluminum and engineering businesses; in technology, with HP’s separation of services and software from printers and PCs; in energy, with Danish industrial conglomerate A.P. Moller-Maersk’s divestiture of its oil businesses; and in health care, with Siemens’ spin-off of its medical technology division. The trend started in the 1980s in the United States and reached Europe in the late 1990s, but it has intensified in recent years, as more vocal investors have pressed for more focused business structures.