corporate combination of two or more independent business corporations into a single enterprise, usually the absorption of one or more firms by a dominant one. A merger may be accomplished by one firm purchasing the other's assets with cash or its securities or by purchasing the other's shares or stock or by issuing its stock to the other firm's stockholders in exchange for their shares in the acquired firm (thus acquiring the other company's assets and liabilities).

Mergers are of several different types: horizontal, if both firms produce the same commodity or service for the same market; market-extensional, if the merged firms produce the same commodity or service for different markets; or vertical, if a firm acquires either a supplier or a customer. If the merged business is not related to that of the acquiring firm, the new corporation is called a conglomerate (q.v.).

The reasons for mergers are various. The acquiring firm may seek to eliminate a competitor; to increase its efficiency; to diversify its products, services, and markets; or to reduce its taxes. Merger activity varies with the business cycle, being higher when business is good.