Equifax is made up of many credit reporting agencies. The most famous Equifax credit reporting agency that sells personal financial information is the one that recently suffered one of the most highly publicized and highly sensitive data breaches in history, impacting 145 million identities. The second largest Equifax credit reporting agency, Equifax Workforce Solutions, is the one that has 296 million employment records that represent, according to the company, “approximately one-third of the working population in the United States.”

It may be even more than that. On a regular basis, a wide range of employers send employment and salary data about their employees to Equifax, including 75% of the country’s Fortune 500 companies, 85% of the federal government workforce, entire state governments and agencies, courts, colleges, and thousands of small businesses nationwide. Financial companies such as mortgage servicers, debt collectors, student lenders, and credit card companies then buy this salary data in the form of individual credit reports. Likewise, prospective employers buy salary data and work history reports about job applicants. Prior to his departure, Equifax’s former CEO Rick Smith estimated that the workforce division “is worth about $9 billion.”

The Work Number database, as it’s known, is also valuable to hackers and fraudsters. As Fast Company previously reported, Equifax Workforce Solutions acknowledged another data theft, separate from the larger hack. For nearly a year, Equifax said in May, criminals had gained unauthorized access to W-2 tax data for an unknown number of…