Alexander Denner, a board member at biotechnology company Biogen Idec (Nasdaq: BIIB), has sold about $1.2 million in shares of the company. Denner, 42, has been serving as managing director of private investment funds affiliated with activist investor Carl C. Icahn since August 2006. Denner, along with Richard Mulligan and Eric Rowinsky, were handpicked by Icahn to serve on the Biogen board, after Icahn won the right to name three board members in the aftermath of his 2010 efforts to have the company…