He used to be in charge at Geron and helped fund the research which led to first human embryonic stem cell line being created in 1998 and now heads another company, BioTime.

BBC: White House stem cell shift expected

BioTime is down 21% over the past year.

FORBES: Biotech Busts And Breakthroughs In May

Notable losers in May included BioTime, a regenerative medicine firm run by Michael West, who was one of the key figures in the early days of embryonic stem cell research, and Cytori Therapeutics, which is trying to commercialize stem cells found in fat for breast reconstruction and other uses.

FORBES: Biotech Busts And Breakthroughs In May