American billionaire business mogul Carl Icahn has announced a substantial investment in Apple and branded the company "extremely undervalued". The announcement sent Apple's value soaring by $12 billion (£7.72 billion).
"We currently have a large position in Apple. We believe the company to be extremely undervalued. Spoke to Tim Cook today. More to come," Icahn said via Twitter.
Icahn added that he is pushing for a larger share buyback at the company, something which he discussed in a "nice" conversation with Tim Cook this week.
Icahn has not revealed the level of investment he has made in the company and it has not yet been disclosed in a regulatory filing.
Following the news, Apple's share price hit $494.66 (£318.38), a six month high. Investor confidence in the company had began to slip amid fears of a decline in innovation since the death of founder Steve Jobs.
Apple said in a statement on Tuesday: "We appreciate the interest and investment of all our shareholders. Tim had a very positive conversation with Mr Icahn today."
Icahn's apparently cosy relationship with Tim Cook contrasts that shared with Michael Dell, the CEO of another company which the businessman holds a large stake in, Dell.
The 77 year old is currently locked in a battle to stop the company being taken over and privatised by a group led by Mr Dell. Icahn has offered a number of alternatives and has publicly called for Mr Dell to leave the company.