GNC got served a lawsuit on Thursday.
Its stock sank by as much as 17% before being halted for news pending.
The Oregon attorney general Ellen Rosenblum alleged in a court filing that the health-and-nutrition-products retailer violated the Oregon Unlawful Trade Practices Act, and sold dietary supplements with potentially dangerous ingredients.
According to the court filing, GNC allegedly sold products that contained either picamilon or BMPEA, both of which do not legally qualify as dietary ingredients.
The former is not used as a prescription drug in the United States although it passes in other countries, while BMPEA is banned by the World Anti-Doping Organisation, according to the filing.
The attorney general alleged that GNC sold over 3,000 products with picamilon in Oregon between January 2013 and June 2015, and as many as 500 products with BMPEA in the same period.
The filing alleged that GNC touted these ingredients as lawful dietary supplements.
GNC shares have dropped 25% year-to-date.
Business Insider has reached out to the company for comment, and we'll update when we hear back.
Here's a chart showing the move lower in trading:
