The Department of Justice may file charges in its generic-drug investigation by the end of the year, Bloomberg reported on Thursday.
The probe is examining whether companies colluded on drug pricing, according to Bloomberg. A number of companies including Mylan and Teva Pharmaceuticals have disclosed subpoenas and are cooperating with authorities, Bloomberg said.
Shares of Mylan, Teva and Endo International plunged after the news, falling 7 percent, 11 percent and 15 percent, respectively.
Lawmakers have recently turned their attention to drug pricing practices in the pharmaceutical industry, calling out price hikes at Valeant Pharmaceuticals and Mylan, among others. The key biotech ETF has fallen 26 percent in 2016, as the sector faces renewed criticism on the campaign trail.