Economic Freedom and Financial Security for Working People Act of 2018 This bill amends the Clayton Act to establish that a corporate acquisition that tends to create a monopsony (i.e., a situation where a single buyer substantially controls the purchasing power in a market for a good or service) is a violation of antitrust law. Currently, the Clayton Act prohibits only acquisitions that would lead to a monopoly (i.e., where a single supplier of a good or service substantially controls the market).