"I think it's obvious it's a zero now," Left told The Street. Left's firm, Citron Research, did not immediately respond to CNBC's request for comment.
Left's new position comes about two months after he told CNBC he had taken a long position in Valeant shares. That said, Left wasn't too optimistic about Valeant at the time, despite his long position.
"You still might say the stock is uninvestable," he said May 17.
Valeant shares have been punished by investors over the past year, falling 90 percent.