Among the stock activity stories for Monday, April 16, from AP Business News:
— Ivanhoe Mines Ltd. shares tumbled to the lowest levels in more than two years on after the government in Mongolia asked for a suspension in activities at a coal mining company that Ivanhoe partially owns.
— Shares of Vringo Inc. soared after it was revealed that billionaire Mark Cuban had taken a major stake in the ringtone company.
— Cobalt International Energy Inc. denied reports that Angolan officials concealed their stakes in an oil venture linked to the company as shares tumbled.
