When the government sets a maximum price in the market. An example of this is rent control laws in New York City. A price ceiling often creates a shortage. The government can set regulations of any kind in any industry. An example would be the government regulation that states seatbelts and airbags are mandatory in the automobile industry.
Regulation often creates new markets that are then ruled by capitalism.
The Sherman Act was established in 1890, which was the first national antitrust law to regulate monopoly and monopoly power. Other similar laws, such as the Clayton Act, followed over time. Antitrust laws are designed to promote competition. Many large-scale mergers and acquisitions are reviewed and sometimes stopped under antitrust laws. Antitrust laws also prohibit any type of inter-company agreements that promote monopoly power.