https://phys.org/news/2018-11-marriott-breach-breakdowns.html

—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.