Data Broker Accountability and Transparency Act of 2018 This bill prohibits data brokers from obtaining or causing to be disclosed personal information relating to any person by making a false, fictitious, or fraudulent statement or representation, including by providing any document that the broker knows or should know to: (1) be forged, counterfeit, lost, stolen, or fraudulently obtained; or (2) contain a false, fictitious, or fraudulent statement or representation. The bill defines "data broker" as a commercial entity that collects, assembles, or maintains personal information concerning an individual who is not a customer or an employee of that entity in order to sell or provide third-party access to the information. Data brokers must establish procedures to ensure the accuracy of the personal information they collect, assemble, or maintain, and provide individuals a cost-free means to review their personal or identifying information. Individuals may dispute the accuracy of their personal information with a written request that the data broker make a correction. Data brokers must provide individuals with a reasonable means of expressing a preference to exclude their information from being used, shared, or sold for marketing purposes.