(USA) Antitrust legislation is designed to prevent businesses from price-setting or other secret collaboration which circumvents the natural forces of a free market economy and gives those engaging in the anti-trust conduct, a covert competitive edge.
Also known as "anti-combines" or "competition" legislation.
The American Department of Justice, Anti-Trust Division has more information, including these statements:
"Antitrust laws apply to virtually all industries and to every level of business, including manufacturing, transportation, distribution, and marketing. They prohibit a variety of practices that restrain trade, such as price-fixing conspiracies, corporate mergers likely to reduce the competitive vigor of particular markets, and predatory acts designed to achieve or maintain monopoly power."
"The Sherman Antitrust Act ... outlaws all contracts, combinations and conspiracies that unreasonably restrain interstate and foreign trade. This includes agreements among competitors to fix prices, rig bids and allocate customers.
"The Sherman Act also makes it a crime to monopolize any part of interstate commerce. An unlawful monopoly exists when only one firm controls the market for a product or service, and it has obtained that market power, not because its product or service is superior to others, but by suppressing competition with anticompetitive conduct.
"The Act is not violated simply when one firm’s vigorous competition and lower prices take sales from its less efficient competitors—that is competition working properly."