Myriad Genetics ( MYGN) was trading higher after the company reported a fiscal second-quarter loss that beat analysts' expectations. After touching a 52-week high of $37.35, the stock was recently up $1.28, or 3.7%, to $36.33.

Shares of MedImmune ( MEDI) were rising 1.7% even after Thomas Weisel Partners downgraded the stock to market-weight from overweight, citing a lack of new drugs in the pipeline. MedImmune, which is set to report fourth-quarter earnings on Wednesday, was recently up 58 cents to $34.22.

Among losers, Mentor ( MNT), a Santa Barbara, Calif.-based maker of breast implants, posted fiscal third-quarter earnings that beat the Thomson First Call consensus, but its shares were still falling. Mentor was down $2.36, or 4.5%, to $50.32.

Elsewhere, Xoma Ltd. ( XOMA) was gaining 10.1% at $3.06, Martek Biosciences ( MATK) was climbing 5.6% to $24.31, and Elan ( ELN) was higher by 1.2% at $13.37.

Meanwhile, Nektar Therapeutics ( NKTR) was slumping 3.7% to $11.73, Biogen Idec ( BIIB) shed 1.1% to $48.49, and Dow component Johnson & Johnson ( JNJ) was off 0.5% at $65.94.

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