EBay said this week that Icahn had taken a 0.82% interest in the company earlier this month and made a non-binding proposal for eBay to spin off its PayPal payments business. EBay has a market capitalization of about $70 billion.
Representatives for both EBay and Icahn did not immediately respond to a request for comment on the size of Icahn's stake.
Icahn told Reuters in an interview he preferred a spinoff of the business to an outright sale. "I personally think you do a spinoff tax-free. After that maybe it could potentially be sold at a great premium," Icahn said.
EBay Chief Executive John Donahoe forcefully rejected Icahn's proposal on Wednesday, saying the company was better off remaining intact.
Icahn has also proposed two nominees to the eBay board. EBay identified them as Icahn Enterprises LP employees Daniel Ninivaggi and Jonathan Christodoro, both of whom Icahn regularly nominates to boards.
Christodoro is a director at Herbalife Inc and Talisman Energy Inc , while Ninivaggi is a director at Federal-Mogul Corp.
Donahoe told Reuters on Wednesday that eBay had a "world-class" board.