Shire plc (NASDAQ: SHPG) is on a buying binge in 2015. After agreeing to be acquired by AbbVie (NYSE: ABBV) for $54.7 billion in July 2014, the deal fell apart in October following the Treasury Department’s revised ruling on foreign domiciles. Shire management turned around and acquired rare disease drug maker NPS Pharmaceuticals, Inc. (NASDAQ: NPSP) in January for $5.2 billion, then added prescription drug maker  Meritage Pharma, Inc. in February for $70 million. After a few months digesting those deals, Shire was back on the acquisition trail in August, paying $300 million for Foresight Biotherapeutics Inc., a clincal stage drug development company. Now it’s agreed to pay $5.9 billion for Dyax Corp. (NASDAQ: DYAX), which Dyax develops plasma kallikrein (pKal) inhibitors for the treatment of HAE (hereditary angioedema), a rare genetic disease. Its lead pipeline product, DX-2930, is a Phase-3 ready asset, offering potential transformative prophylactic therapy for HAE. Shire is clearly expecting big things as DX-2930 has received Fast Track, Breakthrough Therapy and Orphan Drug designations from the FDA, and has achieved Orphan Drug status in the EU.