US medical bill and debt collector American Medical Collection Agency (AMCA) has filed for bankruptcy protection in the aftermath of a disastrous data breach. At least 20 million US citizens have been impacted by the security incident, in which the hacker responsible ransacked AMCA's internal systems to pillage user data including names, Social Security numbers, addresses, dates of birth, and payment card information. Following the disclosure of the data breach and the reveal of its widespread impact, multiple class-action lawsuits were filed against Quest Diagnostics, AMCA, and LabCorp. US regulators are also investigating the incident and now the ruinous consequences of the data breach have led to AMCA's parent company, Retrieval-Masters Creditors Bureau Inc., to voluntarily file for Chapter 11 bankruptcy protection. According to the Chapter 11 declaration (.PDF), filed with the court for the Southern District of New York, AMCA first became aware of a potential security incident when a disproportionate number of credit cards that interacted with the company's web portal were linked to fraudulent transactions.