
The newspaper appointed i-level to the account in 2007, but put the account up for review this year.
The Sun.co.uk reached a record 27.3m unique users in February, overtaking Guardian.co.uk, Telegraph.co.uk, Times Online and Mail Online, to become the UK's most popular national newspaper website, according to recent ABCe results.
Along with The Sun's main website, The Sun also runs a popular Bingo site.
MindShare prised News International's £25m media account from long-term incumbent Carat back in 2005. But NI shifted the digital business to i-level in 2007 as it built its empire away from its traditional newspaper heartland.
Mindshare said that there had been 'ongoing discussions with News International but no formal pitch' for the digital business.