The prominent short-seller David Einhorn raised eyebrows last month when he popped up on Twitter to deny that he had tweeted about the company Herbalife.

Einhorn, a hedge fund manager, said: “Apparently I have a Twitter impersonator.”

What set off Einhorn, the founder of Greenlight Capital, was a post by a since-suspended Twitter account called @Greenlightcap that read: “The $ HLF tug of war will in the end come down to who has more money to play with. I wouldn’t want to be in Bill’s shoes right now #TeamIcahn.”