Twitter reported quarterly revenue that fell short of estimates after the social-media company restructured its advertising sales force.

Fourth-quarter revenue was $717 million. Sales growth of 1 percent slowed dramatically in the period from the 48 percent gain a year earlier. Twitter added 2 million new users, bringing the total number of people who log in monthly to 319 million, the San Francisco-based company said Thursday in a statement.

"2016 was a transformative year as we reset and focused on why people use Twitter: it's the fastest way to see what's happening and what everyone's talking about," said Jack Dorsey, Twitter's CEO. "We overcame the toughest challenge for any consumer service at scale by reversing declining audience trends and re-accelerating usage. As a result, in the fourth quarter, daily active usage accelerated for the third consecutive quarter, and we see this strong growth continuing. While revenue growth continues to lag audience growth, we are applying the same focused approach that drove audience growth to our revenue product portfolio, focusing on our strengths and the real-time nature of our service. This will take time, but we're moving fast to show results."

Twitter has had trouble persuading advertisers to spend more money on its social-media platform as fewer people join. Twitter cut 9 percent of its staff, sold its Fabric developer business to Google and shut down its Vine short-video app.

The company's advertising revenue for the 4Q 2016 totaled $638 million, down slightly year-over-year. Mobile advertising revenue was 89% of total advertising revenue.

Twitter's profit excluding certain items was $119 million. The company's net loss widened to $167 million.