Luminex Corp. ( LMNX - Get Report) was one of Thursday's biggest gainers after swinging to a fourth-quarter profit, boosting shares by 30.6%. Luminex was adding $3.89 to $16.62.

Shares of XenoPort ( XNPT) were up 12.9% after announcing an agreement with drugmaker GlaxoSmithKline ( GSK) to co-develop a new treatment for restless leg syndrome and neuropathic pain. XenoPort was rising $3.26 to $28.50.

Alkermes ( ALKS - Get Report) jumped 12.3% after the company raised its fiscal-year guidance thanks to a solid third quarter. Alkermes was gaining $1.84 to $16.84.

Affymetrix ( AFFX) was rising 6.2% after posting a better-than-expected fourth-quarter profit, despite falling 72% from a year ago. Affymetrix, which manufactures chips used in genetic research and drug development, was up $1.64 to $28.31.

Myriad Genetics ( MYGN - Get Report) said late Wednesday it will sell 3 million shares under an existing shelf registration. It will grant the underwriter a 30-day option to buy an additional 450,000 shares. Myriad was losing $1.22, or 3.3%, to $35.89.

Elsewhere, Arena Pharmaceuticals ( ARNA) was jumping 6% to $14.24, ImClone Systems ( IMCL) was adding 3.6% to $30.50, and Nektar Therapeutics ( NKTR) was gaining 2.8% at $12.64.

Merck ( MRK - Get Report) was off 0.6% to $43.99, and Schering-Plough eased 0.6% to $24.53.