Twitter's revenue in the fourth quarter was strong but the pace of its user growth weakened. The company also confirmed its new partnership with Google. Twitter said it ended 2014 with 288 million monthly users, up 1.4 percent from Sept. 30. The pace of user growth was Twitter's slowest in several quarters.

Twitter said revenue in the three months ended Dec. 31 totaled $479 million, compared to $243 million in the year-ago period. The company also posted a net loss of $125 million in the fourth quarter.

Twitter also projected that revenue in the first quarter would range from $440 million to $450 million.

Twitter has struggled to enlarge its audience, raising questions about whether it can achieve the scale of Facebook, the world's No.1 social network with 1.39 billion users.

Instagram, the photo-sharing app owned by Facebook, recently surpassed Twitter's audience size and announced it had 300 million monthly users.

Following the release of its fourth-quarter earnings results, Twitter CEO Dick Costolo also confirmed the company’s previously rumored new partnership with Google. Twitter had partnered with Google before to surface tweets in search results, but in 2011 it chose not to renew their deal because the terms weren’t favorable enough for the social media company.

"We’ve got the ability to drive attention and aggregate eyeballs to logged out topics and events," Costolo said. "That’s one of the reasons it makes a lot more sense for us now."

He didn’t go into any of the business deals of the agreement, and he said we shouldn’t expect to see the partnership come to fruition for a few months.

During the earnings call, Costolo also blamed an iOS 8 bug and seasonality, saying that the fourth quarter is always Twitter’s slowest in terms of user growth.

"It’s an unforeseen bug as it relates to twitter integration," Costolo told investors. "Once we understood the issue we moved as quickly as we could to minimize the impact on multiple fronts. The problem was complex and affected different users differently."

The company already has deals to deliver data to Microsoft's Bing search engine and to Yahoo, and this week said it will show ads in Flipboard's app for smartphones and tablets.

Twitter additionally has released new features designed to increase usage of its service on mobile devices, including new video features in January. The company has also begun using an algorithm to display important tweets from users' streams when they log onto the service.