Biogen shares were on track to post one of their worst days in history on Friday, after the biotech giant lowered its forecast for 2015 on slower-than-anticipated growth of its multiple sclerosis blockbuster Tecfidera.
The Cambridge, Massachusetts-based company said total sales will grow 6 to 8 percent this year, down from a previous prediction of 14 to 16 percent. Earnings per share, adjusted for some items, are expected to range from $15.50 to $15.95, down from $16.60 to $17 that Biogen predicted earlier this year.
"Biogen's 2Q report is a messy one to say the least," JPMorgan analyst Cory Kasimov wrote in a research note. The shares were down 21 percent Friday afternoon.
So what happened?
Doctors may be spooked about a safety issue with Tecfidera, Biogen said on its earnings call Friday. The concern is about a rare brain infection called PML, for progressive multifocal leukoencephalopathy, which emerged among patients taking an older Biogen drug, Tysabri.