Activist investor Carl Icahn urged Apple Inc. (NASDAQ:AAPL) CEO Tim Cook at a dinner Monday night to buy back $150 billion worth of shares, he said in a tweet.

He plans to meet with Cook again in three weeks to discuss the plan further.

In August, Icahn revealed that he had taken a large stake in Apple after the company announced a record buyback program. Now, he wants to see Apple purchase more of its stock.

Apple has been active in returning cash to shareholders over the last year and a half. In April, the company kicked off a buyback program worth $60 billion by the end of 2015. By June, Apple had already repurchased $16 billion of its shares.