NEW YORK (MarketWatch) – Even though Carl Icahn has made nearly $ 1.3 billion on his Apple Inc. stock AAPL, +2.30% in a little over three months, he still isn’t happy. Apple’s market value has reached $ 710 billion, more than double its closest competitor, but he believes the iPhone maker is actually worth $ 216 a share now, which would value Apple at $ 1.3 trillion. “It seems to us the market is somehow missing a very basic principle of valuation: when a company’s future earnings are expected to grow at a much faster rate than that of the S&P 500, the market should value that company at a higher P/E multiple,” Icahn said. Icahn sent another letter to Apple CEO Tim Cook on Wednesday requesting that Apple increase “the magnitude and rate of share repurchases.” Icahn owned more than 52.7 million shares of Apple as of the company’s Sept. 30 filing. His stake has grown by a whopping $ 1.26 billion since then, as of Apple’s recent trading price of $ 124.71 on Wednesday.