Billionaire investor Carl Icahn said on Wednesday that he has filed a shareholder proposal with Apple for a much smaller stock buyback plan than he has advocated previously, as he continued to pressure Apple to share more of its cash pile. Gave $AAPL notice well be making a precatory proposal to call for vote to increase buyback program, although not at $150 billion level, Icahn said in a tweet. CNBC said Icahns plan calls for a $50 billion buyback program. Icahn had been urging Apple to buy back $150 billion worth of shares.