The reason MJNA tanked today is that it is part of a group that ran up yesterday - stinky pinky stocks in the sector. Also, there was a Seeking Alpha article, by Rolling O Research, "Medical Marijuana Inc's Stock Price Benefits From A $60M Mistake In A Yahoo Blog"
My latest Seeking Alpha article, which increased the knowledge that the $60M "revenue" number from the Yahoo blog post and video had been corrected to mean the entire market, hit that site at 7:03AM EDT.
As more people began to understand that the excitement about MJNA was driven by incorrect data, they sold.