Billionaire investor Carl Icahn, who sparred for years with short-seller William Ackman over the future of Herbalife Nutrition Ltd , on Thursday said he sold roughly $552 million worth of Herbalife stock back to the company, trimming his stake to 21 percent. Icahn said in a regulatory filing that he sold 10.5 million shares back to the company, for $52.50 a share, after having announced last week that he was ready to part with 11.4 million shares. Read more on NewsOK.com