One billion Yahoo accounts were compromised on the eve of a $4.8B sale to Verizon. Yahoo failed to offer multi-factor authentication until March of 2016. The companys neglect for improving security (they still used an MD5 hash to store passwords well into 2013, despite the fact that this has been proven to be weak) leaves them selling to Verizon for a fraction of their previous value. After all, user account data is worth much less if it is no longer secure.”]
Source: https://informationsecuritybuzz.com/articles/yahoos-ripple-effect-multi-factor-imperative/