Biotech stocks left something to be desired Wednesday, losing investor enthusiasm over breakups, regulatory setbacks and earnings.

Nastech ( NSTK) fell after Procter & Gamble Pharmaceuticals, a unit of P&G ( PG), terminated a development and commercialization agreement for Teriparatide, a nasal spray for treatment of osteoporosis. Nastech, which now regains rights to the drug, said it's immediately advancing it into a phase II clinical study on bone mineral density. It expects to recognize about $5.5 million in revenue in the fourth quarter due to termination of the P&G agreement.

Nastech shares slid $5.37, or 38%, to $8.62. It's a component of the Nasdaq biotechnology index, which was also down 22.7 points, or 2.6%, at 858.29.

Momenta ( MNTA) shed another 35 cents, or 6.2%, to $5.32 on Wednesday, as investors continued to react to the FDA's rejection of a generic form of blood-clotting drug Lovenox. Momenta, which partners with Novartis ( NVS) for the drug, on Tuesday said the FDA was concerned with the drug's immunogenicity, or whether the drug could produce an immune response. On Wednesday, the stock was downgraded by Deutsche Securities from buy to hold and by Rodman & Renshaw from market outperform to market perform.

One winner Wednesday was Onyx Pharmaceuticals ( ONXX), which climbed $8.68, or 17.6%, to $58.03. The company said after the market close Tuesday that it earned $555,000, or a penny a share, compared to a loss of $20.1 million, or 49 cents a share, in the comparable year-ago period. Analysts surveyed by Thomson Financial had expected a loss of 21 cents a share.

Bayer, the company's partner for cancer drug Nexavar, reported that the drug generated revenue of $104.6 million in the quarter, up sharply from $45.4 million in the comparable year-ago period. On Wednesday analysts seemed enthusiastic about Nexavar sales -- Lehman Brothers upped its price target to $60 from $54; HSBC Securities upped its target to $61 from $44; and BMO Capital Markets raised its target to $46 from $41.

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