Fascinating as the corporate takeovers of recent years have been--with their "golden parachutes" and junk bonds, "greenmailers" and white knights--it is far from clear what underlying forces are at work, and what their long-term consequences will be. Debate over these questions has become polarized: some see takeover threats as disciplinary mechanisms that induce managers to behave efficiently and move assets to higher valued uses or into the hands of more efficient managers; others claim that corporate raiders have produced few observable increases in operating efficiency, but rather have...