Retrophin ($RTRX), the biotech helmed by hedge funder Martin Shkreli, leapt more than 25% after buying the rights to another drug with the potential to treat a rare disease. Retrophin's latest acquisition is tiopronin, an FDA-approved drug that targets a kidney-stone-forming ailment called cystinuria, affecting about one in every 7,000 people. After the deal, Retrophin raised its annual revenue projection to as much as $35 million, a 60% boost over its last estimate, and said it expects between $60 million and $70 million in 2015. More