Several stocks showed hefty gains over the past four weeks,led by Biogen (BGEN), which was up almost 44 percent byFriday from its close of $22.75 a share on Aug. 31.

The AMEX Biotechnology Stock Index and the Chicago BoardOptions Exchange closed Friday at 152.97 and 145.09,respectively, down slightly from where they were a month ago,at 150.49 and 142.68, respectively.

"Biogen has done really well, and people have upped theirinterest on the news of its big royalty streams," said JosephEdelman, an analyst with Prudential Bache in New York,

Genzyme Corp.'s (GENZ) was also up for the period -- to $44 ashare from its $39.75 a share close on Aug. 28.

Vestar Inc. (VSTR) rose from $8.75 on Aug. 18 to close at $13on Friday, a hike that David Webber, an analyst with AlexBrown & Sons in New York, attributed to promising sales of itslead product, AmBisome, and news that the company won thefirst round of its litigation battle with The Liposome CompanyInc.

Edelman attributed Immunex Corp.'s (IMNX) rise, from $36.50on Aug. 24 to close at $42.50 on Friday, to its three early-stageproducts: PIXY, a blood cell growth factor, and two solublereceptors TNF and IL1, which are showing promising results.

-- Michelle Slade Associate Editor

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