This famous Act banned all combinations and practices that restrained free trade. It ended up banning monopolies, vertical integration, horizontal integration, behind-closed doors trusts, etc. What was this famous legislation called

The Sherman Antitrust Act.

Explanation:

The Sherman Antitrust Act was enacted by the federal on 2nd July 1890. The act was passed in response to the growing competition among the business. The act was named after Senator John Sherman the proponent of the act. The act prohibited charging of unfair prices on farmers and merchants and favoriting large companies.

This act restrained the growth of monopolies who were practices that were trying to stop free trade.

It was an anti-trust act; trusts were the big business markets from which stakeholders would transfer theirs on a single trustee. This created a monopoly in the market disabling other companies.

So, the correct answer is the Sherman Antitrust Act of 1890.