Apple (NASDAQ:AAPL) investors already know that Carl Icahn is on their side. The famed activist investor initiated a position in Apple earlier this year and has been adding to his stake. Icahn's official position in the third quarter has now been officially disclosed in SEC filings. At the end of September, Icahn was sitting on approximately 3.9 million shares worth about $1.9 billion. That was just a 0.4% stake in Apple at the time.

Icahn also published a letter he had written to Tim Cook, in which he indicated he had 4.7 million shares at the time. So far, the position is paying off for Icahn, as Apple has gained 10% so far this quarter. At current prices, his position is valued at $2.5 billion. Additionally, Icahn even expressed an active interest in buying more shares of Apple since he considers it so undervalued.

Icahn joins David Einhorn in pushing Apple to return more cash to shareholders by whatever means necessary. Both Icahn and Einhorn have made aggressive suggestions on how Apple could do so. Apple certainly can and should afford to give more back to investors, even if it chooses to do so on its on terms instead of taking advice from Icahn or Einhorn.

In this segment of Tech Teardown, Erin Kennedy discusses the details of Icahn's Apple investment with Evan Niu, CFA, our tech and telecom bureau chief.