8. Massive Security Breaches At Yahoo Endanger $4.83 Billion Acquisition By Verizon

Yahoo this year reported not one, but two massive security breaches that threatened to undo a deal under which the Internet portal company would be acquired by communications giant Verizon for $4.83 billion.

The first shock came in September when Yahoo disclosed that a 2014 cyberattack had compromised more than 500 million user accounts – and admitted it had known about the incident since earlier in the summer. In December Yahoo announced that another security breach in August 2013 exposed information from 1 billion users – the largest known security data breach at any company.

News of the two incidents raised questions if Verizon would go ahead with the planned acquisition – or would at least seek a lower acquisition price given that some now see Yahoo as damaged goods. By year's end, Verizon was still mulling its next move.