11.5 : 寡头垄断下的公共政策：反垄断法

Antitrust laws are regulations that promote fair competition and protect consumers from unfair business practices. In the context of oligopolies, antitrust laws prevent anticompetitive practices, such as price fixing, that can harm consumers.

These laws prohibit actions that can restrict competition, such as predatory pricing, tying agreements, and mergers that could reduce competition.

Further, Antitrust laws are used to enforce against oligopolies that collude to control the market through anticompetitive practices.

The Sherman Antitrust Act of 1890 significantly developed antitrust laws in the United States. The act prohibits certain business activities that it considers anti-competitive. These include any businesses attempting to monopolize a market, conspiring with competitors to control prices or other actions that restrain trade or commerce.

One of the act's main provisions outlaws all combinations that restrain trade between states or foreign nations. This prohibition applies to formal cartels and any agreement to fix prices, limit industrial output, share markets, or exclude competition.

In conclusion, antitrust laws serve as a crucial safeguard, ensuring that oligopolistic markets remain competitive, dynamic, and beneficial for consumers.