Biotechnology companies shares down at the close of trading

Shares of some top biotechnology companies were down at the close of trading:

Amgen Inc. fell $5.53 or 3.3 percent, to $162.38.

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Biogen Idec fell $12.44 or 3.1 percent, to $389.27.

Celgene Corp. fell $4.00 or 3.4 percent, to $114.72.

Gilead Sciences Inc. fell $.76 or .7 percent, to $102.94.