Thursday's Health Winners & Losers

Updated from 11:45 a.m. EDT

Health care and biotech stocks followed the broader market's upward trend Thursday, thanks to merger and acquisition talk coming out of MedImmune (MEDI Quote).

Shares of the company jumped 15.3% after it indicated the possibility of a sale of the company. MedImmune's board has already authorized management to field potential offers. The stock added $5.79 to $43.63.

The Amex Biotechnology Index, of which MedImmune is a component, climbed 2.5%. Fellow components Imclone Systems (IMCL Quote) and Gilead Sciences (GILD Quote) rose 2.9% and 3%, respectively.

Elsewhere, the Amex Pharmaceutical Index was 1.1% higher, thanks to gains of 1.6% in Pfizer (PFE Quote), 2.3% in Amgen (AMGN Quote) and 0.9% in Schering-Plough (SGP Quote).

On the losing side, Genentech (DNA Quote) fell 1.3%, even after the company reported a 43% rise in first-quarter results compared to the year-ago period. Adjusted earnings of 74 cents a share topped the Thomson First Call consensus. Still, shares were off $1.06 at $81.63.

Cell Therapeutics (CTIC Quote), which jumped 13% Wednesday after its Xyotax drugs received "fast track" designation from the Food and Drug Administration, completely erased the previous session's gain.

DOR BioPharma (DORB Quote) rejected a bid from Cell Therapeutics, claiming that the price offered in January was inadequate. Cell Therapeutics shares lost 35 cents, or 19.1%, to $1.48.

Among other decliners, MedcoHealth (MHS Quote) slid 39 cents to $71.32. Adolor (ADLR Quote) was off 5 cents, or 1.4%, at $3.64.