David Einhorn is up against the short seller who brought down Valeant

In his second-quarter letter to investors, Greenlight Capital's David Einhorn disclosed that he is long Chemours.
The stock is up 7% on the news.
Andrew Left, the short seller from Citron Research whose questions brought Valeant Pharmaceuticals to its knees last October, disclosed a short position in the company in June.
So we have ourselves a bit of a tiff here.
First, a little about Chemours: It's a chemicals company that DuPont spun off into its own company. Greenlight started buying it durin