Einhorn doubles down on Chemours, Citron's Left responds

David Einhorn, president of Greenlight Capital.
Katie Young | CNBC

Greenlight Capital's David Einhorn gave up on some investments, but doubled down on one controversial stock, according to a letter sent to his hedge fund's clients Tuesday.

Einhorn said the fund exited a long position in Macy's at a loss after the company reduced financial guidance. He also covered a losing short position in Intuitive Surgical as competition didn't ramp up as expected.

However, the hedge fund manager added to his stake in the chemical firm spun off from DuPont, Chemours.

"We began buying in Q4 2015, believing that TiO2 [titanium dioxide] prices were at or near the bottom. As the market caught up to our thinking, the shares began a rapid recovery, and we held an incomplete position," Einhorn wrote in the letter. "In June, a short recommendation achieved widespread publicity and caused the shares to temporarily retreat, enabling us to complete purchasing our stake at attractive prices."

Einhorn is referencing noted short seller Andrew Left of Citron Research, who posted a negative report on the company in June saying it "is a bankruptcy waiting to happen" as "DuPont dumped these [legal] liabilities into spin-off Chemours."

When asked to comment by CNBC PRO, the short seller told us: