Investor Carl Icahn has spoken with Apple Chief Executive Tim Cook again to discuss a potential stock buyback, CNBC reported on Monday. Icahn has been asking for a $150 billion buyback publicly and privately to Apple's Cook since August. According to CNBC, he had "a good conversation" as the two men believe Apple is undervalued.

Last month, Icahn sent a letter to Apple Chief Executive Tim Cook pushing him for the massive $150 billion buyback at the company.

Icahn in August disclosed via Twitter that he was talking to Cook. Earlier this month he also said he had dinner with Apple's boss for the buyback.

Icahn owns roughly 4.7 million shares in the technology giant. He claims that that Apple shares could trade at $700 with a larger stock buyback.