Companies lost more than the half of their value on the stock market

Has anybody else on quimby noticed that some companies lost more than 50% of their market value? Does somebody have an explanation for that ?

Server and Company? Hard to explain why, if we cannot see the Company in question. Send PM, if you want discretion.

It´s on QUIMBY for example AMAZON AIRLINES. But like a miracle the value went back to the level before they suddenly lost 50% of value..

Or Vuelamerica from PTY. Went down 55% and then went up again 125%