MGM Resorts International said a cyberattack last summer cost it more than $100 million in lost revenues, fees, and other expenses, according to a quarterly financial filing reported by the Las Vegas Review-Journal. The company said the incident, which began in June 2020, involved unauthorized access to customer payment card information. The attack was discovered in July and affected customers at a number of MGM properties, the filing stated. The company has been working with federal and international law enforcement and cyber security firms to investigate and take corrective action.