CommentaryWhen to call a halt

A little bit of information is a dangerous thing. A little bit of information disseminated widely can become a major problem.

Gilead Sciences Inc. experienced the phenomenon first hand at the FDA advisory panel meeting on its Vistide anti-CMV retinitis compound. Investors dumped GILD stock after a Dow Jones reporter filed a story early in the course of the March 15 meeting focusing on carcinogenicity of the drug in a rat model. As investors usually do, they sold first and waited to ask questions later, taking more than $8 off the stock in short order.