's biggest brand-name product, the multiple sclerosis treatment Copaxone.
The Israeli company said Saturday the decision from the U.S. District Court for the Southern District of New York covers several patents, the last of which expires in 2015, and that it prevents other drugmakers from selling their versions of the drug until then. It also said the decision should prevent the Food and Drug Administration from approving generic versions of the drug until 2014.
U.S.-traded shares of the company rose 4.5 percent, or $1.71, to close at $39.72, while the Standard & Poor's 500 index fell 1.6 percent.
Teva had sued Mylan Laboratories Inc., Momenta Pharmaceuticals Inc., Sandoz Inc. and Natco Pharmaceuticals, accusing the rival companies of infringing on patents covering the drug's chemical composition, method of use and the manufacturing process behind the product.
Teva is the 10th largest global pharmaceutical company, according to drug data firm IMS Health, and Copaxone is its main brand-name offering. It expects $3.8 billion in sales this year from the drug. Teva is primarily a maker of generic drugs.
The ruling removes a major uncertainty hanging over Teva shares, Credit Suisse analyst Michael Faerm wrote in a note to investors. The analyst called it a "resounding victory" for Teva.
"Although a majority of investors expected a Teva win ... the magnitude of the potential impact of a loss to Teva's earnings and share price kept many investors on the sidelines, and this event will likely bring some of them into the stock," Faerm wrote.
Cambridge, Mass.-based Momenta said in a separate statement that it intends to appeal. Its shares tumbled $3.81, or 22 percent, to $13.20.
Mylan, based in Canonsburg, Pa., said in a brief statement it intends to evaluate its options for appeal. It added that the decision does not affect its earnings guidance. Its stock dropped 43 cents, or 2 percent, to $20.80.
A representative from Sandoz, a unit of Swiss drugmaker Novartis, declined comment. Natco, which is based in India, did not respond to a request for comment Monday from The Associated Press.
Copaxone also faces a potential challenge from a Biogen Idec Inc. oral MS drug labeled BG-12. Biogen recently asked the Food and Drug Administration to approve the drug, which has shown in clinical trials to be more effective than Copaxone.
Sales for the Teva drug will likely decline rapidly if BG-12 receives regulatory approval and hits the market, Cowen and Co. analyst Ken Cacciatore said in a research note. But he also said the launch of a competing drug may help Teva shares. He noted that investors already have a sales decline factored into their view of the stock, and if Copaxone does better than expected, the shares may benefit.
Teva also said earlier this month that a longer-acting version of Copaxone did well in a late-stage clinical trial. Copaxone is injected daily. The newer version is designed to be taken only three times a week.
Cacciatore said Teva could shift some of its customers to that version if it receives approval.