CALGARY – Billionaire investor Carl Icahn reveals he has bought more than 61.5 million shares of Talisman Energy Inc. for a 5.97 per cent stake in the Calgary-based oil and gas producer. In a U.S. regulatory filing, his firm says it believes Talisman’s assets are “undervalued” and that it intends to have conversations with management about “asset sales or potential corporate restructuring,” as well as “the possibility of shareholder board representation.”