Biotech stocks tumble on phantom terror as analysts struggle to explain

The Nasdaq biotech index ($IBB) slumped another 5.6% on Thursday, and it's apparently anyone's guess as to why. As The Wall Street Journal reports, the latest decline follows an inexplicable jump the day before, and the industry's exchange-traded fund has fallen roughly 20% since hitting an all-time high in February. Analysts are having trouble diagnosing the problem, with some pointing to pricing concerns over high-fliers like Gilead Sciences ($GILD) while others blame a rise in skepticism among generalist investors. Article (sub. req.)