After hearing positive news from Bluebird Bio on Wednesday, Jim Cramer has a warning for investors who are salivating over the cancer immunotherapy plays.
"I need to warn you: this is a high-risk group and I have noticed a pattern that is less than ideal," the "Mad Money" host said.
Bluebird is a development-stage gene therapy company that is a leading player for cancer immunotherapy. It announced positive interim phase 1 clinical trial data for its multiple myeloma therapy, which appeared to have few severe side effects, though it was a small study.
Cramer noticed that when a company like Bluebird reports good news, only the company's stock will rally. The rest of the group will barely move. But when a company reports bad news, the entire cohort gets crushed.