When a baker needs eggs, she buys them from a chicken farmer. That is a market transaction. Alternatively, the baker can raise her own chickens. That is vertical integration. Existing theories claim that integration reduces costs, or increases overall profit, but they have overlooked an important part of integration: the acquisition payment. When that is taken into account, their conclusions become invalid. This book first turns Robinson's predatory monopoly theory into a short-run rational merger and acquisition theory. It then applies a simultaneous model to derive long-run results. Rather than obsessively promoting integration, this book proves that there is a certain optimal number of integrations and that sometimes it is more profitable to disintegrate or outsource.