TWITTER BOOKED A net loss in the first quarter because of stock compensation costs, but its results surpassed Wall Street’s expectations thanks to a sharp increase in advertising revenue.

But shares of the short messaging service dropped sharply after the results came out because of investor concern about its ability to grow its user base and keep its existing users engaged.

Twitter said Tuesday that it had a loss of $132.4 million, or 23 cents per share, in the January-March quarter. That compares with a loss of $27 million, or 21 cents per share, a year ago when Twitter was still privately held. Adjusted earnings were $183,000, or roughly breakeven on a per share basis.

Revenue more than doubled to $250 million from $114 million. Twitter’s advertising revenue was $226 million, about 80 per cent of which came from mobile advertising.

Analysts polled by FactSet had expected an adjusted loss of 3 cents per share on revenue of $241.5 million. Twitter’s own forecast in February was for revenue between $230 million and $240 million.

Shares of San Francisco-based Twitter fell $4.52, or 10.6 percent, to $38.10 in after-hours trading after the results came out. If it opens at this price on Wednesday, it will be the stock’s lowest point since Twitter went public last fall. The stock had closed up $1.89, or 4.6 percent, at $42.62.

Twitter went public last November, setting a price of $26 per share for its stock, which then soared amid hungry investor demand. The high-flying stock peaked in December at $74.73 and then declined sharply.

Twitter had 255 million monthly users at the end of March, up 25 per cent from a year ago. That’s just about what Sterne Agee analyst Arvind Bhatia was expecting, though 2 million lower than Wall Street’s consensus. The analyst called the quarter’s results “mixed,” noting that user metrics were better than they were in the final quarter of 2013 — Twitter’s first as a public company — but not as strong as Wall Street had expected.

Comparisons

Twitter has said that it is focusing on expanding its audience and encouraging people who do use its short messaging service to use it more often, but the company has not been growing its user base as fast as its investors would like.

By comparison, Facebook has 1.28 billion users and professional networking service LinkedIn had 277 million users at the end of 2013. WhatsApp, the messaging app Facebook has agreed to buy for $19 billion, recently passed the 500 million user milestone.

“We had a very strong first quarter. Revenue growth accelerated on a year over year basis fueled by increased engagement and user growth,” said CEO Dick Costolo in a statement.

“Timeline views,” which measure how often users refresh their own or someone else’s Twitter feed, increased 15 percent in the quarter to 157 billion. Wall Street had expected of a higher number at 165 billion, according to Bhatia.

Advertising revenue per thousand timeline views, another closely watched measurement, reached $1.44 in the first quarter, more than double the figure from a year ago. But the number declined from the fourth quarter of 2013, when it was $1.49.

Twitter gave a conservative revenue forecast for the current quarter and for all of 2014. The company expects revenue of $270 million to $280 million for the April-June period, compared with analysts’ expectations of $273.3 million.

For the full year, Twitter expects revenue of $1.2 billion to $1.25 billion, compared with analysts’ forecast of $1.24 billion.

Read: Samsung profits rise slightly despite sliding smartphone revenue >

Read: Facebook’s plan for its mobile apps: grow userbase now, make money later >