Here's Why Shares of bluebird bio Slumped Today

The biotech has been flying high, up 55% year to date through yesterday, buoyed by an upcoming EU approval for Zynteglo, its gene therapy for the treatment of transfusion-dependent beta-thalassemia that gained a positive opinion from the European Medicines Agency's Committee for Medicinal Products for Human Use. An OK from the European Commission should come in the next couple of months.