The Securities and Exchange Commission has stopped trading in 15 companies because of "questionable trading and social media activity."
The action follows suspensions of other companies that have been the targets of efforts to use social media to "artificially inflate" their stock prices, the SEC said.
The 15 companies include: Bebida Beverage Co., Blue Sphere Corp., Ehouse Global Inc. and Eventure Interactive Inc.
"We proactively monitor for suspicious trading activity tied to stock promotions on social media, and act quickly to stop that trading when appropriate to safeguard the public interest," said Melissa Hodgman, acting director of the SEC's division of enforcement, in a release.
In January, the SEC issued an alert on investing based on social media.