Shares in Twitter have dropped 11 percent to their lowest level since the company was floated after reporting a loss and disappointing growth in user numbers.
The number of active users of the social networking site grew by 5.8 percent to 255 million, but that growth was lower than expected.
Twitter made a net loss of $US132 million in the first three months of 2014.
It posted quarterly revenue of $US250 million, $US226 million of which was made through advertising.
The results revealed slowing momentum at a company which exuberant investors had once argued could match Facebook.