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

Amgen Inc. fell $.20 or .2 percent, to $133.02.

Biogen Idec rose $1.24 or .4 percent, to $345.84.

Celgene Corp. rose $.05 or .1 percent, to $91.36.

Gilead Sciences Inc. rose $.56 or .6 percent, to $101.28.