Biogen halted its Alzheimer's drug trial. Here's what that means for biotech investors

9:48 AM ET Thu, 21 March 2019

Biogen shares tumble after the drug maker discontinued late-stage trials of an Alzheimer's treatment. Geoff Porges, senior biotech analyst at SVB Leerink, joins "Squawk Box" by phone to discuss what that means for the stock.