Ticketmaster has alerted customers about a data security incident that may have compromised their personal information. The company is investigating the breach and is cooperating with U.S. federal law enforcement authorities. The incident, which occurred in May, has led to warnings for customers to take action to protect their data. Ticketmaster has expressed deep regret over the hack, which has particularly affected Canadian customers. The delayed notification has triggered backlash from customers over the privacy breach.