The micro-blogging site is losing users...
Twitter shares have been hit by volatile after-hours trading after its latest results showed a decline in monthly active usage in the last quarter.
Revenues for the whole of 2015 were up 58% to $2.2bn representing what the company called "another very strong year for Twitter."
But investors were instead focused on the number of active users of the site. The total number of these was flat compared to the previous quarter but according to Twitter's own preferred underlying measure it fell.
As social media has evolved and gone 'mobile' the company has struggled, while photo and video focused platforms like Instagram and Snapchat have enjoyed massive growth - particularly with younger users.
Shares slumped by as much as 14% before recovering the losses to leave the price flat.
It follows a catastrophic three months in which the company has lost half its value. Twitter has been making changes to the way it works but is lagging behind market leader Facebook on a number of fronts including earnings and user numbers.
Starting today you can choose to try our new feature, so you'll never miss important Tweets from people you follow: https://t.co/fS1axkDiUh— Twitter (@twitter) February 10, 2016
In its latest results the company said: "We saw a decline in monthly active usage in the fourth quarter, but we've already seen January monthly actives bounce back to third quarter levels. We're confident that, with disciplined execution, this growth trend will continue over time."
Total monthly active users (MAUs) were 320 million for the quarter, lower than expected and unchanged from the previous period. It was the first flat quarter-on-quarter performance since the company floated on the stock market in 2013.
Twitter disappointed traders with its revenue expectations for the current first quarter - at $595m-$610m these were well below Wall Street forecasts.
The micro-blogging site saw revenues of $710m in the three months to the end of December, up 48% from the same period last year thanks to a surge in advertising turnover.
Twitter habitually makes losses and it was in the red by $90m in the fourth quarter, though this was 28% down year-on-year. For the full year, losses narrowed by 10% to $521m.
The results came hours after Twitter announced a major change on Wednesday, saying it would now show the best algorithimically-selected
At the moment, most people see a constant stream of updates in reverse chronological order.
The weak results are likely to stoke investor concerns over stalled growth, which a series of initiatives since the return of founder Jack Dorsey last summer have failed to reverse.
Brian Blau, research director at Gartner, said: "With no increase in new users, but otherwise good financial performance, Twitter hasn't yet shown how it can rise from the troubling spot of not being able to grow the business."