Billionaire investor Carl Icahn said Thursday that he has spoken to Tim Cook and will be having dinner with the Apple CEO to discuss the "magnitude" of a stock buyback.
(Read more: Carl Icahn's effect on Apple: Traders weigh in )
"Spoke to Tim. Planning dinner in September. Tim believes in buyback and is doing one. What will be discussed is magnitude," Icahn tweeted @Carl_C_Icahn.
The activist investor revealed last week via Twitter that he had taken a large position in Apple, which is estimated to be worth more than $1 billion. Icahn told CNBC last Tuesday that a bigger buyback was a "no brainer" for Apple and that it would enhance the stock value tremendously, which he said was largely undervalued.