Piper Jaffray analyst David Amsellem upgraded Horizon Pharma (HZNP) to Overweight saying the company's planned acquisition of Hyperion Therapeutics (HPTX) is the kind of diversifying transaction he was hoping to see. Amsellem believes Hyperion's ultra-orphan drug Ravicti, its liquid formulation of glycerol phenylbutyrate for urea cycle disorders, is a "game-changer" for Horizon that will drive shares higher. He raised his price target for Horizon shares to $31 from $21. The biopharmaceutical company closed yesterday up $3.97 to $25.78 after announcing the acquisition.