The number of Twitter users each month has stalled, as the social networking site posted a fall in revenue.
Twitter said average monthly active users in the three months to the end of June was 328 million, the same as in the previous quarter.
Shares in the company fell 5% in pre-market trading as analysts had been expecting 328.8 million monthly users.
The firm's net losses also widened as it took a $55m (£42m) impairment charge and revenue fell by 4.7% to $573.9m.
The 328 million users in the second quarter was a 5% rise on the period in 2016.
It comes as Facebook reported soaring revenues and profits.
Twitter is facing competition not only from Facebook, but also messaging app Snapchat.
Twitter, which became a publicly listed company in November 2013, has been looking to increase revenue through live-streaming deals.
However, in April it lost a deal to live-stream Thursday night NFL games this year to Amazon.com.
"Until Twitter can return to revenue growth, we expect advertisers to devote their ad budgets to platforms with better targeting, reach, and scale," Michael Pachter, an analyst at financial services firm Wedbush wrote in a pre-earnings note.
Its advertising revenue fell 8% to $489m, but was well ahead of analyst estimates.
The company's net loss widened to $116.5m from $107.2m a year earlier.
Twitter chief executive Jack Dorsey said: "We're strengthening our execution, which gives us confidence that our product improvements will continue to contribute to meaningful increases in daily active usage.
"We're also encouraged by the progress we're making executing against our top revenue generating priorities as we focus on making Twitter the best place to see and share what's happening, where you can see every side and perspective."