Anti-trust law, which is known as competition law outside of the United States, prohibits companies from acting in the manner that reduces competition in markets. The basis of the market economy is that companies aggressively compete to sell to customers. Anti-trust law helps make that happen. Back in 1911, the market for refined oil, such as gasoline, was almost entirely controlled by one company, called Standard Oil, which was owned by John Rockefeller, probably the richest man in the world. It was anti-trust law that provided the legal foundation for breaking up Standard Oil into 33 companies, in order to enhance competition.