Twitter struggles to expand user base with new plans

San Francisco

TWITTER Inc added no new users in the fourth quarter, confirming the fears of advertisers and investors - that the social-media site is in trouble.

The company has faced sharp criticism over slowing growth in its audience since its 2013 initial public offering. Even as chief executive officer Jack Dorsey rolled out efforts to make its product more mainstream, by some measures Twitter's user base shrank from the third quarter.

Twitter tried to divert W…