Activist investor Carl Icahn said Apple's stock should be trading at $216, valuing the company at more than $1 trillion. At $216 per share, Apple would be worth about $1.3 trillion (!). The company is valued at just over $700 billion currently and its record high of $124.92 hit on Wednesday.

Icahn said Apple should be trading at 20 times earnings per share.

"This is why we continue to own approximately 53 million shares worth $6.5 billion, and why we have not sold a single share," Icahn said in a letter .

"Also, to the extent Apple introduces a TV in FY 2016 or FY 2017, we believe this 20X multiple is conservative," he wrote.

Icahn, one of Apple's top 10 investors, has long urged the company to buy back more shares and raise its dividend.