Biotech stock United Therapeutics (UTHR) has emerged as a leading member of an industry group that has been among the best performers over the past two years. The stock boasts a best-possible 99 IBD Composite Rating, ranking it alongside stalwarts such as Celgene (CELG) at the top of IBD's Medical-Biomedical/Biotech industry group. As of Friday, the group was ranked No. 16 out of 197. United Therapeutics, which produces drugs to treat