Well suppose the CEO of ACME Pharma knows a major drug trial just failed. If she sold massively and pushed the price down, wouldn't that cause the lower price

Well suppose the CEO of ACME Pharma knows a major drug trial just failed. If she sold massively and pushed the price down, wouldn't that cause the lower price to be reflective of the actual real valuation of ACME (which is lower because they don't have a major drug now). Of course, I wouldn't want to be the guy on the other side of that trade. But then again a casual grandma probably doesn't want to be on the other side of the trade of a multimillion dollar research team either.