2013.03.1107:35:26UTC+00Twitter, social media are fertile ground for stock hoaxes

David Einhorn a prominent short seller raised eyebrows last month when he popped up on Twitter to disavow that he had tweeted about Herbalife Ltd.

"Apparently I have a twitter impersonator," said the hedge fund manager, adding that he had no plans "to tweet about stocks." What set off Einhorn  was a post by a 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."

Einhorn isn't the only short seller who has been impersonated on Twitter, which has become an important source of information for many investors. In late January, shares of Audience Inc and Sarepta Therapeutics Inc plunged following tweets that were purported to be from short-selling researchers.

"Twitter pump and dump schemes are obviously something for the market to be concerned about, even if they are just a new way for people to do schemes that have been done forever," said Keith McCullough, chief executive officer at Hedgeye Risk Management in New Haven, Connecticut.

The FBI monitors FaceBook and Twitter, and said that social media will be a big part of securities fraud.