LAS VEGAS (AP) — Activist investor Carl Icahn has upped his stake in casino giant Caesars Entertainment. The billionaire, who is seeking fundamental changes in the Las Vegas-based company, on Monday disclosed in a securities filing that recent stock purchases now put his stake at 17.75 percent. The filing with the Securities and Exchange Commission shows Icahn-controlled hedge funds purchased 15 million shares for $126.75 million. Icahn revealed last month he had a 10 percent stake in the company and wanted changes including board representation and a say on who will be the casino operator's next CEO.