Carl Icahn on Twitter: "We currently have a large position in APPLE. We believe the company to be extremely undervalued. Spoke to Tim Cook today."
More from Icahn: "Discussed my opinion that a larger buyback should be done now. We plan to speak again shortly."
Update: Statement from Apple: "We appreciate the interest and investment of all our shareholders. Tim [Cook] had a very positive conversation with Mr. Icahn today."