Consumers Union, a nonprofit advocacy group, called on Congress to hold hearings on firms that collect and sell personal financial information beyond what is included in the nation’s three main credit bureaus following a Washington Post story on the industry.

Dubbed the “fourth bureau,” the firms gather data from sources as varied as payday loans and magazine subscriptions and sell the information to lenders and other financial firms. Federal regulations do not always require companies to disclose when they share such information or with whom, and many consumers do not realize they exist.

“The activities of the ‘fourth bureau’ unfairly use consumers’ data to draw potentially harmful and unreliable conclusions about their creditworthiness and ability to pay,” the group wrote in a letter to several congressional committees.

Consumers Union proposed that lawmakers consider requiring those firms to provide toll-free numbers and free annual reports.