Twitter reports $645m loss for 2013
The loss was expected by analysts, who highlighted Twitter’s revenues, which rose 110% last year to reach $665m, the BBC reports.
But a reported slow growth in user numbers was a bigger concern for investors.
Twitter averaged 241 million monthly users in the last quarter of the year, up just 3.8% on the previous quarter.
That represents a slowdown compared with a growth rate of 10% seen at the beginning of 2013.
Timeline views were down nearly 7%, suggesting users were refreshing their feeds less often.
Shares fell as much as 12% in after-hours trading on Wednesday.