Marriott's revelation that as many as 500 million guests may have been affected by a data breach at Starwood hotels, which it bought two years ago, ranks among the largest hacks ever. It is not clear if some of those included in the final tally are individuals who were counted during every stay.
For comparison, here are some of the worst data breaches in history:
—Yahoo, by far, takes the prize for worst data breach, with a 2013 hack affecting 3 billion accounts.
—EBay asked all of its 145 million active users in 2014 to change their passwords as a precautionary measure because of a hack into personal information. The company was not sure how many people were actually affected by the breach.
—Equifax suffered a breach in 2017 that affected about 148 million people. It discovered the hack in July of 2017, but didn't disclose it until September 7.
—In 2014, 83 million accounts were compromised at JPMorgan Chase.
—Insurer Anthem suffered a hack in 2015 that may have compromised records for nearly 80 million people.
—In 2013, Target was attacked by hackers, affecting 41 million people.