This was true of the Sherman Antitrust Act of 1890, state-level antitrust laws passed before Sherman, and the Clayton Act of 1914. The view that antitrust law is a policy to protect the public interest and promote competition has lost credibility among experts and practitioners. Empirical data show that most complaints against mergers are filed by competitors of the merger partners, not public interest groups. When complaints were filed and legal action announced, the stock prices of those rivals increased , demonstrating that the proposed merger would have been competitive. While researchers have not ruled out the possibility that antitrust enforcement may have deterred some anti-competitive mergers, their results clearly indicate the more common outcome was protection of rival producers from increased competition due to efficient mergers.
Most mergers are efficient and create social benefits.
Mergers are an efficient response to the expansion of free trade and spread of market institutions worldwide following the collapse of communism. In the U.S., deregulation of domestic public utilities has created new national markets where only strictly regulated regional markets existed previously. And new technologies such as the Internet are creating new profit opportunities for firms able to capitalize on the convergence of communications, computer, and entertainment enterprises. Mergers and acquisitions are particularly valuable in restructured markets such as airlines, banking, radio, telephone, television, natural gas, and electric power. Mergers can create new corporate entities large enough to enter new markets and compete with local and regional monopolies.