Shares in Twitter have fallen 10% after the social media company’s revenue forecast fell short of expectations.
Revenue for the first quarter of 2019 is now expected to be between $715m and $775m, below analysts’ forecasts.
Twitter also warned that its operating costs could rise 20% in 2019.
The share fall came despite the company reporting profits of $255m (£197m) for the final quarter of 2018, more than double the $91m profit it made a year earlier, as advertising revenues grew.
The rising costs come as social media companies face increased pressure to police the content of their sites more closely, following scandals over mental health, user privacy, hate speech and political campaigning.
Twitter said it had removed millions of abusive accounts as part of its clean-up effort, prompting a fall in monthly users.
Currently 321 million people use Twitter, as calculated on a monthly basis, down from 330 million a year earlier.
Despite the decline, revenue in the last quarter increased 24% to $909m as video advertising grew.