On May 10, a compromise to Citi Account Online that impacted roughly one percent of North America Citi-branded credit card accounts was discovered as part of routine monitoring and immediately rectified. While Citi Cards' Account Online system was compromised, the main cards processing system was not. Other Citi consumer banking online systems were not accessed or compromised.
Upon discovery, internal fraud alerts and enhanced monitoring were placed on all accounts deemed at risk. Simultaneously, rigorous analysis began to determine the precise accounts and type of information accessed. The majority of accounts impacted were identified within seven days of discovery. By May 24, we confirmed the full extent of information accessed on 360,069 accounts. An additional 14 accounts were confirmed subsequently. To determine the cardholder impact required analysis of millions of pieces of data.