Yahoo might not have the greatest number of email subscribers, but it did just manage to top the list of security breaches. In 2013, the web provider was hit by a huge hack, the extent of which wasn’t confirmed until this year. But according to CNN Money, the data of three billion Yahoo users was compromised by this breach, making it the worst cyberattack ever. And, as CNN Money points out, this security breach isn’t to be confused with the one that was announced in September 2016—right around the time Yahoo was in the process of being acquired by Verizon—which affected only about 500 million accounts. Still, the number of compromised accounts in both cases have led to Yahoo suffering the two worst security hacks in history.