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What: Momenta Pharmaceuticals (NASDAQ:MNTA) ended the day up 11% after spending most of the afternoon in negative territory. The come-from-behind victory for the day stems from a patent trial and appeal board ruling that claims 1-20 of a patent on Teva Pharmaceutical Industries' (NYSE:TEVA) three-times-weekly version of its multiple sclerosis drug Copaxone weren't patentable.

So what: The petitioner to the appeal board was actually Mylan (NASDAQ:MYL) and Amneal Pharmaceuticals because they want to launch a generic version of the drug, but Momenta is also developing a generic version of three-times-weekly Copaxone -- and currently sells the only generic version of the daily Copaxone -- so the ruling affects Momenta as well.

Mylan ended the day down 5%, but that had to do with ongoing controversy over pricing of its EpiPen. Presidential candidate Hillary Clinton tweeted out that there was "no justification for these price hikes."

Teva Pharmaceutical ended the day down 3%. Three-times-weekly Copaxone is an important drug for Teva, but it's a large company, so the damage isn't as severe as the benefit to Momenta.

Shares of Momenta's partner Novartis (NYSE:NVS), which will sell the drug, hardly moved on the news, which isn't too surprising given how large a drugmaker it is. The three-times-weekly version of Copaxone won't really move the needle of Novartis' sales.

Now what: Momenta and Novartis have filed their own lawsuit against Teva over patents on the three-times-weekly version of Copaxone, which is scheduled to be heard on Sept. 26. The lawsuit is separate from the patent board decision, but the fact that the board found the claims unpatentable is certainly a good sign for Momenta and Novartis' chance in court next month.

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