Stocks of biologic, specialty drugmakers fall on Clinton vow of plan to fight 'price gouging'

Stocks of makers of biologic and "specialty" drugs plunged Monday after Democratic presidential frontrunner Hillary Clinton said she'll soon release a plan to address "price gouging" in the industry.

Clinton's announcement on Twitter follows news that drugmaker Turing Pharmaceuticals had hiked the price of a 53-year-old drug for a potentially deadly parasitic infection from $13.50 per pill to $750 overnight. Because the drug, Daraprim, treats patients with compromised immune systems, the 5,456 percent prike hike sparked outrage from medical groups representing doctors who care for patients with HIV and other infectious diseases.

One drugmaker, Mallinckrodt Pharmaceuticals, saw shares drop more than 10 percent. Top 20 drugmakers whose products include biologic or specialty drugs posted share drops of more than 2 percent. And the S&P 500 Biotechnology Index dropped 3.17 percent.