According to security firm InfoArmor, the Yahoo database was sold for $300,000 on the dark web. Yahoo still considers the breaches in 2014 and 2013 as unrelated events. The investigation indicates that the user account information that was stolen did not include passwords in clear text, payment card data, or bank account information. It is still unclear who is behind the attack, security experts attributed the 2013 Yahoo hack to a Russian APT group. Yahoo is sending email notifications to the additional affected user accounts.”]
Source: http://securityaffairs.co/wordpress/63813/data-breach/2013-yahoo-hack-3b-accounts.html