Yahoo have revealed that the information of 1 billion users has been compromised following a breach in 2013, making it the largest data breach ever.
The number was thought to be half that number at when first disclosed in 2014 but new information has suggested that it is much more.
Yahoo has blamed hacker groups working on behalf of the government for the breach.
Verizon were due to buy Yahoo’s core internet business for $4.83 billion, but a spokesperson now says that "we will review the impact of this new development before reaching any final conclusions."
Yahoo shares were down 2.4 percent to $39.91 in extended trading.