Shares of Abgenix were among the best-performing health-related stocks Thursday, soaring 48% after the company agreed to be acquired by Amgen ( AMGN - Get Report) for $2.2 billion in cash plus the assumption of debt.

Abgenix shareholders will receive $22.50 a share in cash, representing a 54% premium to Wednesday's closing price of $14.65. "Abgenix is a natural strategic fit for Amgen given our strong existing relationship," Amgen said in a statement. "This investment reflects Amgen's commitment to our pipeline and our growing confidence in the future success of both panitumumab and denosumab."

Amgen expects the acquisition to be dilutive by 5 cents to 10 cents a share during 2006 and 2007 and accretive thereafter, assuming commercial success of panitumumab, which is being studied as a potential therapy for colorectal cancer and for head and neck cancer. The deal is expected to close during the first quarter of 2006. Shares of Abgenix were trading up $7.07 to $21.72, while shares of Amgen rose $2.63, or 3%, to $79.41.

Shares of Matria Healthcare ( MATR) rose 9% after the company announced plans to buy privately held CorSolutions Medical for $445 million in cash. Matria expects the acquisition of the disease management services company to be accretive to earnings in 2006 and "significantly" accretive to earnings during 2007 and beyond. CorSolutions expects to post operating profits of $32 million on sales of more than $120 million for 2005. Matria projects the deal will close by year's end or shortly thereafter. Shares of Matria were trading up $3.10 to $39.47.

Zimmer Holdings ( ZMH) rose 2% after the orthopedic implant company said it plans to buy back up to $1 billion worth of stock through December 2007. "Based upon the repayment of our Centerpulse and Implex acquisition debt, we believe that share repurchases are currently an appropriate way to take advantage of our continued strong cash flow," the company said. "As we have said, we will continue to look for strategic acquisitions that meet our demanding criteria, but this share repurchase program gives us another option to deploy cash with the expectation of building shareholder value." Zimmer shares recently had gained $1.06 to $70.57.

Shares of BioCryst Pharmaceuticals ( BCRX - Get Report) fell 4% after the company said that it will sell 2.2 million shares of stock at $13.46 apiece to a group of institutional investors. The price represents a 13% discount to Wednesday's closing price of $15.55. "This financing provides BioCryst with the resources we need to pursue broad clinical trials of peramivir in patients with seasonal and life-threatening strains of influenza," the company said. Shares were down 56 cents to $14.99.

Other health care volume movers included Pfizer ( PFE), up 2 cents to $22.87; Elan ( ELN), up $1.07 to $13.97; Merck ( MRK), up 45 cents to $29.65; Schering-Plough , down 23 cents to $19.62; SFBC International , down $1.26 to $16.40; Kos Pharmaceuticals down $15.03 to $54.90; Bristol-Myers Squibb ( BMY), down 5 cents to $21.89; Novavax ( NVAX), down 6 cents to $4.34; and Johnson & Johnson ( JNJ), down 2 cents to $60.09.