Shares of Forward Pharma and Acorda Therapeutics dropped Friday afternoon, after documents revealed both firms lost separate drug patent lawsuits.
Shares of Forward lost nearly 20 percent before being halted Friday around noon ET, pending the release of material news. Biogen shares closed the day up nearly 2 percent.
"We are pleased with the decision of the patent office ... and intend to defend this [drug] portfolio," a Biogen spokesperson told CNBC in a statement following Friday's news. Forward didn't immediately respond to CNBC's request for comment.
Separately, court documents showed Acorda Therapeutics lost an infringement case on four patents for multiple sclerosis treatments against several major drug firms, including Teva Pharmaceuticals, Mylan Pharmaceuticals — a subsidiary of Mylan — and Roxane Laboratories.
Acorda shares fell more than 20 percent lower after being halted twice Friday morning — once for trade volatility and once pending the release of material news.
"We are disappointed by the Court's decision and are preparing our appeal," Ron Cohen, Acorda's chief executive officer said in a statement.
Despite Friday's losses, shares of Forward and Acorda are still trading in green territory for the year. Acorda is up about 12 percent, and Forward is up more than 40 percent, year-to-date.