I'm a little late with this story but thought it worth sharing anyway. Yahoo announced last week that they had another security breach (in addition to the 500 million hacked accounts earlier this year). This newly disclosed breach, which happened in 2013, involved 1 Billion Yahoo accounts. As seen in the title, that's a lot of zeros.
It appears Yahoo's user data has been compromised multiple times in recent years. If you've used Yahoo in the past and cancelled your account, please make sure you didn't use the password you had at Yahoo anywhere else. If you have a Yahoo account, why are you still reading this? Go cancel it .... now.