Carl Icahn will be sending an open letter to Apple CEO Tim Cook on Thursday, the activist investor said on Twitter.
Click here for Icahn tweet.
Apple shares traded up above 1.7 percent following the tweet. (Get the latest quote here.)
Apple declined to comment on the news.
Icahn will be on CNBC's "Halftime Report" Thursday at 12 p.m. ET.
Icahn also took to Twitter to say that it was just over a year since his firm announced its large position in Apple, and that the stock is up 50.6 percent since then.
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Icahn has previously pushed for Apple to engage in stock more buybacks, and trumpeted its pipeline of new products.