Well-known activist investor and billionaire Carl Icahn tweeted that he has now boosted his stake in Apple (NASDAQ: AAPL ) by $500 million to $3.6 billion, calling the company a no-brainer investment, and is continuing his fight for increased share buybacks. He has now issued an open letter, calling his fellow shareholders to arms. In his seven-page letter, he notes that the S&P 500 trades at a 71% premium to Apple, which he calls a "dramatic valuation disconnect." Icahn's annoyance with Apple's enormous cash hoard is obvious, but does his proposal make sense?

In this segment of Tech Teardown, Erin Kennedy discusses Carl Icahn and Apple with Evan Niu, CFA, our tech and telecom bureau chief. The number of Apple bears has been on the rise recently ever since the stock fell from its high in 2012 and lagged the market considerably in 2013, but Icahn has defended Apple's prospects. He believes the company's unrivaled customer loyalty will be the key to it maintaining pricing and margins going forward, and he's still bullish on Tim Cook's leadership. He also sees Apple getting into Ultra HD televisions, which he thinks could generate as much as $40 billion in revenue annually.

With Icahn having backed off from his initial call for $150 billion in buybacks and revising down to $50 billion, Evan sees that number as reasonable. He agrees that Apple does have too much cash on the books, and could see a $50 billion share repurchase before the end of the fiscal year in September as making sense.