Facebook revenue growth slows, costs weigh on profit

Shares of the world's largest internet social network fell as much as 3.1 percent in after-market trading on Wednesday.

Facebook has warned that 2015 will be a year of heavy investments as it steps up efforts to expand a collection of products that include messaging service WhatsApp, photo-sharing service Instagram and virtual reality headset maker Oculus Rift.

Facebook's operating expenses rose 83 percent in the first quarter as R&D costs jumped 133 percent and marketing and sales spending nearly doubled.

The company said it had 1.44 billion monthly active users, with 87 percent of them accessing its service on smartphones and other mobile devices.

Net income attributable to stockholders fell to $509 million, or 18 cents per share, in the three months ended March 31, from $639 million, or 25 cents per share, a year earlier.

Excluding items, the company earned 42 cents per share.

The world's largest internet social network said revenue rose to $3.54 billion from $2.50 billion. Revenue from advertising was $3.32 billion, a 46 percent rise from a year earlier.

Analysts on average had expected a profit of 40 cents per share and revenue of $3.56 billion.

(Reporting by Bill Rigby in Seattle and Abhirup Roy in Bengaluru; Editing by Saumyadeb Chakrabarty)