Health Winners & Losers: Momenta

Health stocks skidded into the weekend on relatively light news Friday -- just around the corner from the start of second-quarter earnings.

The Amex and Nasdaq biotechnology indices were down 0.4% and 0.6%, respectively, while the Amex pharmaceutical index fell 1.7%, in line with the broader markets.

Notably, there wasn't a single component on the Amex pharma index that ended the day in the green. Schering-Plough (SGP Quote), Sanofi-Aventis (SNY Quote), and Forest Laboratories (FRX Quote) all registered declines of more than 2%. But Teva Pharmaceutical (TEVA Quote) fell the hardest, giving up 7.2% to $41.78.

Momenta Pharma (MNTA Quote) said on Friday that the Food and Drug Administration accepted its abbreviated new drug application for a generic version of Teva's MS drug Copaxone. The news sent Momenta's shares up 81 cents, or 6.2%, to $13.89. Teva announced that it would file a patent infringement lawsuit against Momenta, as expected.

Meanwhile, London-based Silence Therapeutics said Friday that the Opposition Division of the European Patent Office overturned European Patent EP 1 230 375 , Cancer Research Technology and Alnylam's (ALNY Quote) "Glover patent," which covers Alnylam's gene-silencing technology. Alnylam shares fell 37 cents, or 1.3%, to $28.96.

Elsewhere, Repros Therapeutics (RPRX Quote) said that in a midstage study its lead experimental drug Proellex significantly relieved pain in women with endometriosis, a condition that involves a growth of uterine tissue outside the uterus. Shares edged up 15 cents, or 1.7%, to $9.05.

A couple of analyst actions. Piper Jaffray analyst Caroline Stewart downgraded Elan (ELN Quote) to sell from neutral, on the premise that the available data on and current risk associated with the company's Alzhiemer's drug candidate don't warrant the appreciation in the stock. Shares gave up $1.92, or 5.2%, to $34.90.