The Sherman Anti-Trust Act outlawed monopolistic business practices.
The Sherman Anti-Trust Act was the first measure by Congress to prohibit trusts. It was passed by Congress in 1890. A trust was when stockholders in multiple companies transferred their stock shares to a single group of trustees. Thus a whole industry area could be dominated by a single "trust" organization, destroying the free market of business competition. . This was a monopolistic practice which the Sherman Anti-Trust Act ended.