I knew data brokerage was big but I didn’t realise it was this big. From The Data Revolution by Rob Kitchin, loc 1039:
Epsilon is reputed to own data on 300 million company loyalty card members worldwide, with a databank holding data related to 250 million consumers in the United States alone (Edwards 2013). Acxiom is reputed to have constructed a databank concerning 500 million active consumers worldwide (about 190 million individuals and 126 million households in the United States), with about 1,500 data points per person, its servers processing over 50 trillion data transactions a year, and its turnover exceeding one billion dollars (Singer 2012a). It also manages separate customer databases for, or works with, 47 of the Fortune 100 companies (Singer 2012a). Datalogix claim to store data relating to over a trillion dollars’ worth of offline purchases (Edwards 2013). Other data broker and analysis companies include Alliance Data Systems, eBureau, ChoicePoint, Corelogic, Equifax, Experian, ID Analytics, Infogroup, Innovis, Intelius, Recorded Future, Seisint and TransUnion.