The perpetrators of a cyberattack on MGM Resorts International, one of the world's largest casino companies, in early 2020 are believed to be a highly capable Western hacking group according to private security companies investigating the incident. MGM only disclosed the breach over a year after it occurred, revealing that details such as name, address, and phone number of 10.6 million guests of MGM properties were accessed without authorization. Financial details such as credit card and bank account numbers were also compromised for an unspecified number of guests. Cyber security experts investigating the attack said it was likely carried out by an experienced group of hackers either state-sponsored or financially motivated, given the scale and sophistication involved. The long delay in disclosure and limited information provided by MGM has drawn criticism and prompted an investigation by Nevada gaming authorities into the casino operator's response and compliance with breach notification rules.