DETROIT Jan 26, 2006 — Billionaire investor Kirk Kerkorian is acquiring 12 million shares of General Motors Corp. stock, matching the number of shares he sold in December, a federal regulatory filing showed on Wednesday. Kerkorian's private equity firm, Tracinda Corp., bought 5 million shares of GM stock on Monday for an average purchase price of $21.40, or approximately $107 million, it said in a filing with the Securities and Exchange Commission. On Tuesday, Tracinda agreed to purchase an additional 7 million GM shares in a private transaction for $22.25 per share, or approximately $155.8 million. Those purchases would boost...